U.S. patent application number 17/512947 was filed with the patent office on 2022-05-05 for liquid ejecting apparatus.
The applicant listed for this patent is Seiko Epson Corporation. Invention is credited to Yusuke MATSUMOTO, Toru MATSUYAMA.
Application Number | 20220134743 17/512947 |
Document ID | / |
Family ID | |
Filed Date | 2022-05-05 |
United States Patent
Application |
20220134743 |
Kind Code |
A1 |
MATSUMOTO; Yusuke ; et
al. |
May 5, 2022 |
Liquid Ejecting Apparatus
Abstract
A liquid ejecting apparatus includes a head unit, and a drive
signal output unit that outputs the drive signal. The head unit
includes an ejection portion that ejects a liquid, a first rigid
substrate, and a first connector including a first terminal, the
drive signal output unit includes a second rigid substrate, a
second connector including a second terminal that outputs the drive
signal, a D/A converter, and a drive signal output circuit, the
first connector is provided on the first rigid substrate, the
second connector, the D/A converter, and the drive signal output
circuit are provided on the second rigid substrate, one of the
first connector and the second connector has a receptacle shape,
the other has a plug shape, and the first connector and the second
connector are fitted so that the first terminal and the second
terminal are in direct contact with each other.
Inventors: |
MATSUMOTO; Yusuke;
(Shiojiri, JP) ; MATSUYAMA; Toru; (Matsumoto,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Seiko Epson Corporation |
Tokyo |
|
JP |
|
|
Appl. No.: |
17/512947 |
Filed: |
October 28, 2021 |
International
Class: |
B41J 2/045 20060101
B41J002/045 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 29, 2020 |
JP |
2020-181651 |
Claims
1. A liquid ejecting apparatus comprising: a head unit that
includes a piezoelectric element that is driven with supply of a
drive signal and ejects a liquid by driving the piezoelectric
element; and a drive signal output unit that outputs the drive
signal, wherein the head unit includes an ejection portion that
ejects the liquid, a first rigid substrate that propagates the
drive signal to the ejection portion, and a first connector
including a first terminal to which the drive signal is input, the
drive signal output unit includes a second rigid substrate, a
second connector including a second terminal that outputs the drive
signal, a D/A converter that converts basic drive data, which is a
digital signal, into a basic drive signal, which is an analog
signal, and a drive signal output circuit that amplifies the basic
drive signal and outputs the drive signal, the first connector is
provided on the first rigid substrate, the second connector, the
D/A converter, and the drive signal output circuit are provided on
the second rigid substrate, one of the first connector and the
second connector has a receptacle shape, the other of the first
connector and the second connector has a plug shape, and the first
connector and the second connector are fitted so that the first
terminal and the second terminal are in direct contact with each
other.
2. The liquid ejecting apparatus according to claim 1, wherein the
first rigid substrate includes a first surface and a second surface
facing the first surface, the head unit includes an ejection
surface on which the liquid is ejected, and a shortest distance
between the first surface and the ejection surface is shorter than
a shortest distance between the second surface and the ejection
surface, and a shortest distance between the second surface and the
second rigid substrate is shorter than a shortest distance between
the first surface and the second rigid substrate.
3. The liquid ejecting apparatus according to claim 1, wherein when
viewed in a plan view in a direction in which the liquid is ejected
from the ejection portion, the second rigid substrate overlaps the
first rigid substrate.
4. The liquid ejecting apparatus according to claim 1, wherein the
first rigid substrate and the second rigid substrate are stacked
and coupled by fitting the first connector and the second connector
so that the first terminal and the second terminal are in direct
contact with each other.
5. The liquid ejecting apparatus according to claim 1, wherein the
first connector has a plug shape, and the second connector has a
receptacle shape.
6. The liquid ejecting apparatus according to claim 1, wherein at
least one of the first connector and the second connector is a
floating connector.
7. The liquid ejecting apparatus according to claim 1, wherein the
first connector includes a first insulator portion, the second
connector includes a second insulator portion, and at least one of
the first insulator portion and the second insulator portion
contains glass fiber.
8. The liquid ejecting apparatus according to claim 1, wherein at
least one of the first terminal and the second terminal contains a
copper alloy.
9. The liquid ejecting apparatus according to claim 8, wherein at
least one of the first terminal and the second terminal is
gold-plated.
10. The liquid ejecting apparatus according to claim 1, wherein the
first connector includes a first fixing portion fixed to the first
rigid substrate, the second connector includes a second fixing
portion fixed to the second rigid substrate, and at least one of
the first fixing portion and the second fixing portion contains a
copper alloy.
11. The liquid ejecting apparatus according to claim 10, wherein at
least one of the first fixing portion and the second fixing portion
is tin-plated.
Description
[0001] The present application is based on, and claims priority
from JP Application Serial Number 2020-181651, filed Oct. 29, 2020,
the disclosure of which is hereby incorporated by reference herein
in its entirety.
BACKGROUND
1. Technical Field
[0002] The present disclosure relates to a liquid ejecting
apparatus.
2. Related Art
[0003] Liquid ejecting apparatuses such as an ink jet printer eject
a liquid such as ink filled in a cavity from a nozzle by driving a
piezoelectric element serving as a drive element provided in a
print head included in a head unit using a drive signal, and form
characters and images on a medium. Since the piezoelectric element
is a capacitive load like a capacitor when viewed electrically, it
is necessary to supply a sufficient current in order to operate the
piezoelectric element of each nozzle. Therefore, in the
above-mentioned ink jet printer, a drive circuit supplies a
high-voltage drive signal amplified by an amplifier circuit to a
head to drive a piezoelectric element.
[0004] For example, JP-A-2018-051772 discloses an ink jet printer
that drives a piezoelectric element and ejects a liquid from a
nozzle by supplying a drive signal output by a drive signal
generation circuit to the piezoelectric element included in an
ejection module. Further, JP-A-2019-130821 discloses an ink jet
printer that drives a piezoelectric element and ejects a liquid
from a nozzle by supplying a drive signal output by a drive circuit
to the piezoelectric element included in a head module.
[0005] However, in view of the fact that the number of
piezoelectric elements included in the liquid ejecting apparatus
has been further increasing in recent years, the ink jet printers
described in JP-A-2018-051772 and JP-A-2019-130821, when
propagating a high-voltage, high-current drive signal for driving a
piezoelectric element, there is room for further improvement from
the viewpoint of reducing the disturbance of a drive signal
waveform caused by an inductance component generated in a
propagation path.
SUMMARY
[0006] According to an aspect of the present disclosure, there is
provided a liquid ejecting apparatus including a head unit that
includes a piezoelectric element that is driven with supply of a
drive signal and ejects a liquid by driving the piezoelectric
element, and a drive signal output unit that outputs the drive
signal, in which the head unit includes an ejection portion that
ejects the liquid, a first rigid substrate that propagates the
drive signal to the ejection portion, and a first connector
including a first terminal to which the drive signal is input, the
drive signal output unit includes a second rigid substrate, a
second connector including a second terminal that outputs the drive
signal, a D/A converter that converts basic drive data, which is a
digital signal, into a basic drive signal, which is an analog
signal, and a drive signal output circuit that amplifies the basic
drive signal and outputs the drive signal, the first connector is
provided on the first rigid substrate, the second connector, the
D/A converter, and the drive signal output circuit are provided on
the second rigid substrate, one of the first connector and the
second connector has a receptacle shape, the other of the first
connector and the second connector has a plug shape, and the first
connector and the second connector are fitted so that the first
terminal and the second terminal are in direct contact with each
other.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIGS. 1A and 1B are diagrams showing a functional
configuration of a liquid ejecting apparatus.
[0008] FIG. 2 is a diagram showing an example of waveforms of drive
signals.
[0009] FIG. 3 is a diagram showing an example of a waveform of a
drive signal.
[0010] FIG. 4 is a diagram showing a configuration of a drive
signal selection circuit.
[0011] FIG. 5 is a diagram showing decoding contents in a
decoder.
[0012] FIG. 6 is a diagram showing a configuration of a selection
circuit corresponding to one ejection portion.
[0013] FIG. 7 is a diagram for describing the operation of the
drive signal selection circuit.
[0014] FIG. 8 is a diagram showing a configuration of a drive
circuit.
[0015] FIG. 9 is an explanatory diagram showing a schematic
structure of the liquid ejecting apparatus.
[0016] FIG. 10 is an exploded perspective view of a head unit and a
drive signal output unit when viewed from a -Z side.
[0017] FIG. 11 is an exploded perspective view of the head unit and
the drive signal output unit when viewed from a +Z side.
[0018] FIG. 12 is a bottom view of the head unit when viewed from
the +Z side.
[0019] FIG. 13 is an exploded perspective view showing a structure
of an ejection head.
[0020] FIG. 14 is a cross-sectional view when a head chip is
cut.
[0021] FIG. 15 is a plan view of the head unit and the drive signal
output unit shown in FIGS. 10 and 11 when viewed from the +Z
side.
[0022] FIG. 16 is a side view of a wiring substrate included in the
head unit and a wiring substrate included in the drive signal
output unit shown in FIGS. 10 and 11 when viewed from the -X
side.
[0023] FIGS. 17A to 17C are diagrams showing the structure of a
connector.
[0024] FIG. 18 is a cross-sectional view taken along line
XVIII-XVIII shown in FIGS. 17A to 17C.
[0025] FIGS. 19A to 19C are diagrams showing the structure of a
connector.
[0026] FIG. 20 is a cross-sectional view taken along line XX-XX
shown in FIGS. 19A to 19C.
[0027] FIG. 21 is a diagram showing a state where the connector and
the connector are fitted.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0028] Hereinafter, preferred embodiments of the present disclosure
will be described with reference to the drawings. The drawings used
are for convenience of description. The embodiments to be described
below do not unduly limit the contents of the present disclosure
described in the scope of claims. In addition, all of the
configurations to be described below are not necessarily essential
configuration requirements of the present disclosure.
1. Functional Configuration of Liquid Ejecting Apparatus
[0029] First, the functional configuration of a liquid ejecting
apparatus 1 according to the present embodiment will be described
with reference to FIG. 1. The liquid ejecting apparatus 1 according
to the present embodiment will be described by taking, as an
example, an ink jet printer that forms a desired image on a medium
by ejecting ink as an example of a liquid onto the medium. Such a
liquid ejecting apparatus 1 receives image data propagated by wired
communication or wireless communication from an external device
such as a computer provided externally, and forms a desired image
on a medium by ejecting ink to the medium at a timing based on the
received image data.
[0030] FIGS. 1A and 1B are diagrams showing a functional
configuration of the liquid ejecting apparatus 1. As shown in FIGS.
1A and 1B, the liquid ejecting apparatus 1 includes a control unit
10, a head unit 20, and a drive signal output unit 50.
[0031] The control unit 10 generates and outputs various signals
for controlling the head unit 20 and the drive signal output unit
50 based on image data supplied from an external device (not
shown). The control unit 10 has a main control circuit 11 and a
power supply voltage generation circuit 12. A commercial voltage,
which is an AC voltage, is input to the power supply voltage
generation circuit 12 from a commercial AC power supply (not shown)
provided outside the liquid ejecting apparatus 1. The power supply
voltage generation circuit 12 generates, for example, a voltage VHV
which is a DC voltage having a voltage value of 42 V based on the
input commercial voltage, and outputs the voltage to the head unit
20. Such a power supply voltage generation circuit 12 is an AC/DC
converter that converts an AC voltage into a DC voltage, and
includes, for example, a flyback circuit and the like, and a DC/DC
converter and the like that convert the voltage value of the DC
voltage output by the flyback circuit. The voltage VHV generated by
the power supply voltage generation circuit 12 is supplied to the
head unit 20 and used as power supply voltages having various
configurations of the head unit 20, and is also supplied to the
drive signal output unit 50 via the head unit 20. In addition to
the voltage VHV, the power supply voltage generation circuit 12 may
generate voltage signals of voltage values used in each portion of
the liquid ejecting apparatus 1 including the control unit 10, the
head unit 20, and the drive signal output unit 50, and output the
voltage signals to each corresponding configuration.
[0032] Image data is input to the main control circuit 11 from an
external device such as a host computer provided outside the liquid
ejecting apparatus 1 via an interface circuit (not shown). The main
control circuit 11 generates various signals for forming an image
on the medium according to the input image data, and outputs the
signals to the corresponding configurations.
[0033] Specifically, the main control circuit 11 performs
predetermined image processing on image data input from an external
device, and then outputs the image-processed signal to the head
unit 20 as an image information signal IP. The image information
signal IP output from the main control circuit 11 is an electric
signal such as a differential signal, and is output as, for
example, a high-speed communication signal based on a peripheral
component interconnect express (PCIe) communication standard. In
addition, examples of the image processing executed by the main
control circuit 11 include color conversion processing for
converting the image signal input from the external device into
color information of red, green, and blue and then converting the
converted color information into color information corresponding to
the color of the ink ejected from the liquid ejecting apparatus 1,
and halftone processing for binarizing color information that has
undergone the color conversion processing. The image processing
executed by the main control circuit 11 is not limited to the color
conversion processing and the halftone processing described
above.
[0034] As described above, the main control circuit 11 generates
the image information signal IP that controls the operation of the
head unit 20 and outputs the signals to the head unit 20. Such a
main control circuit 11 includes, for example, a system on a chip
(SoC) including one or a plurality of semiconductor devices having
a plurality of functions.
[0035] The head unit 20 includes a head control circuit 21, a
differential signal restoration circuit 22, a voltage conversion
circuit 23, and ejection heads 100-1 to 100-n.
[0036] The voltage VHV is input to the voltage conversion circuit
23. Then, the voltage conversion circuit 23 generates and outputs a
voltage VDD, which is a predetermined voltage value of the input
voltage VHV and is, for example, a DC voltage of 5 V. Such a
voltage conversion circuit 23 includes, for example, a DC/DC
converter and the like. Then, the voltage VDD generated by the
voltage conversion circuit 23 is supplied to each portion of the
head unit 20 and also to the drive signal output unit 50.
[0037] The head control circuit 21 outputs a control signal for
controlling each portion of the head unit 20 based on the image
information signal IP input from the main control circuit 11.
Specifically, the head control circuit 21 generates a differential
signal dSCK obtained by converting a control signal for controlling
the ejection of ink from each of the ejection heads 100-1 to 100-n
into a differential signal and differential signals dSIa1 to dSIam,
. . . , dSIn1 to dSInm corresponding to the ejection heads 100-1 to
100-n, respectively, based on the image information signal IP, and
outputs the signals to the differential signal restoration circuit
22.
[0038] The differential signal restoration circuit 22 restores each
of the input differential signal dSCK and differential signals
dSIa1 to dSIam, . . . , dSIn1 to dSInm into the clock signal SCK,
and the corresponding print data signals SIa1 to SIam, . . . , SIn1
to SInm, and outputs the signals to the corresponding ejection
heads 100-1 to 100-n.
[0039] Specifically, the head control circuit 21 generates a
differential signal dSCK including a pair of signals dSCK+ and
dSCK-, and outputs the differential signal to the differential
signal restoration circuit 22. The differential signal restoration
circuit 22 generates a clock signal SCK, which is a single-ended
signal, by restoring the input differential signal dSCK, and
outputs the clock signal to the ejection heads 100-1 to 100-n.
[0040] The head control circuit 21 generates differential signals
dSIa1 to dSIam including a pair of signals dSIa1+ to dSIam+ and
dSIa1- to dSIam-, and outputs the differential signals to the
differential signal restoration circuit 22. The differential signal
restoration circuit 22 generates print data signals SIa1 to SIam,
which are single-ended signals, by restoring the input differential
signals dSIa1 to dSIam, and outputs the print data signals to the
ejection head 100-1.
[0041] The head control circuit 21 generates differential signals
dSIn1 to dSInm including a pair of signals dSIn1+ to dSInm+ and
dSIn1- to dSInm-, and outputs the differential signals to the
differential signal restoration circuit 22. The differential signal
restoration circuit 22 generates print data signals SIn1 to SInm,
which are single-ended signals, by restoring the input differential
signals dSIn1 to dSInm, and outputs the print data signals to the
ejection head 100-n.
[0042] That is, the head control circuit 21 generates a
differential signal dSCK, which is the basis of the clock signal
SCK commonly input to the ejection heads 100-1 to 100-n, and
differential signals dSI11 to dSI1m, . . . , dSIn1 to dSInm which
are the basis of the print data signals SI11 to SI1m, . . . , SIn1
to SInm individually input to the ejection heads 100-1 to 100-n,
and outputs the differential signals to the differential signal
restoration circuit 22. The differential signal restoration circuit
22 restores the differential signal dSCK and the differential
signals dSI11 to dSI1m, . . . , dSIn1 to dSInm to generate the
clock signal SCK and the print data signals SI11 to SI1m, . . . ,
SIn1 to SInm, which are single-ended signals, and outputs the
signals to the corresponding ejection heads 100-1 to 100-n.
[0043] Here, each of the differential signal dSCK and the
differential signals dSIa1 to dSIam, . . . , dSIn1 to dSInm output
from the head control circuit 21 may be a differential signal of a
low voltage differential signaling (LVDS) transfer method, or a
differential signal of various high-speed communication methods
such as low voltage positive emitter coupled logic (LVPECL) or
current mode logic (CML) other than LVDS.
[0044] Further, the head control circuit 21 generates a latch
signal LAT and a change signal CH as control signals for
controlling the ink ejection timing from the ejection heads 100-1
to 100-n based on the image information signal IP input from the
main control circuit 11, and outputs the signals to the ejection
heads 100-1 to 100-n.
[0045] Further, the head control circuit 21 generates basic drive
data dA and dB which are the basis of drive signals COMA and COMB
for driving the ejection heads 100-1 to 100-n based on the image
information signal IP input from the main control circuit 11, and
outputs the data to the drive signal output unit 50.
[0046] The drive signal output unit 50 includes drive circuits 51a
and 51b. The basic drive data dA is input to the drive circuit 51a.
The drive circuit 51a generates a drive signal COMA by converting
the input basic drive data dA into an analog signal and then
amplifying the converted analog signal in class D based on the
voltage VHV, and outputs the drive signal to the ejection heads
100-1 to 100-n included in the head unit 20. The basic drive data
dB is input to the drive circuit 51b. The drive circuit 51b
generates a drive signal COMB by converting the input basic drive
data dB into an analog signal and then amplifying the converted
analog signal in class D based on the voltage VHV, and outputs the
drive signal to the ejection heads 100-1 to 100-n. Further, the
drive signal output unit 50 generates a reference voltage signal
VBS which is a reference potential when ink is ejected from the
ejection heads 100-1 to 100-n by boosting or stepping down the
voltage VDD, and outputs the reference voltage signal to the
ejection heads 100-1 to 100-n. That is, the drive signal output
unit 50 includes two class D amplifier circuits that generate drive
signals COMA and COMB, and a step-down circuit or booster circuit
that generates a reference voltage signal VBS.
[0047] Here, in the present embodiment, the description has been
made that the drive circuit 51a generates the drive signal COMA and
outputs the drive signal COMA to the ejection heads 100-1 to 100-n,
the drive circuit 51b generates the drive signal COMB and outputs
drive signal COMB to the ejection heads 100-1 to 100-n. However,
the present disclosure is not limited thereto. For example, the
drive signal output unit 50 may include n drive circuits 51a that
output drive signal COMA corresponding to each of the ejection
heads 100-1 to 100-n, and n drive circuits 51b that output drive
signal COMB corresponding to each of the ejection heads 100-1 to
100-n. The drive circuits 51a and 51b need only be able to amplify
the analog signals corresponding to the input basic drive data dA
and dB based on the voltage VHV, and may include a class A
amplifier circuit, a class B amplifier circuit, or a class AB
amplifier circuit.
[0048] The ejection head 100-1 included in the head unit 20 has
drive signal selection circuits 200-1 to 200-m and head chips 300-1
to 300-m corresponding to the drive signal selection circuits 200-1
to 200-m, respectively.
[0049] The print data signal SIa1, the clock signal SCK, the latch
signal LAT, the change signal CH, and the drive signals COMA and
COMB are input to the drive signal selection circuit 200-1 included
in the ejection head 100-1. The drive signal selection circuit
200-1 included in the ejection head 100-1 generates a drive signal
VOUT by selecting or not selecting the waveform included in the
drive signals COMA and COMB at the timing defined by the latch
signal LAT and the change signal CH based on the print data signal
SIa1, and supplies the drive signal to the head chip 300-1 included
in the ejection head 100-1. Thereby, a piezoelectric element 60,
which will be described later, of the head chip 300-1 is driven,
and ink is ejected from the corresponding nozzles as the
piezoelectric element 60 is driven.
[0050] Similarly, the print data signal SIam, the clock signal SCK,
the latch signal LAT, the change signal CH, and the drive signals
COMA and COMB are input to the drive signal selection circuit 200-m
included in the ejection head 100-1. The drive signal selection
circuit 200-m included in the ejection head 100-1 generates a drive
signal VOUT by selecting or not selecting the waveform included in
the drive signals COMA and COMB at the timing defined by the latch
signal LAT and the change signal CH based on the print data signal
SIam, and supplies the drive signal to the head chip 300-m included
in the ejection head 100-1. Thereby, a piezoelectric element 60,
which will be described later, of the head chip 300-m is driven,
and ink is ejected from the corresponding nozzles as the
piezoelectric element 60 is driven.
[0051] That is, each of the drive signal selection circuits 200-1
to 200-m switches whether or not to supply the drive signals COMA
and COMB as the drive signals VOUT to the piezoelectric elements 60
included in the corresponding head chips 300-1 to 300-m.
[0052] Here, the ejection head 100-1 and the ejection heads 100-2
to 100-n differ only in the input signal, and the configuration and
operation are the same. Therefore, the description of the detailed
configuration and operation of the ejection heads 100-1 to 100-n
will be omitted. Further, in the following description, when it is
not necessary to particularly distinguish the ejection heads 100-1
to 100-n, they may be simply referred to as the ejection head 100.
Further, the drive signal selection circuits 200-1 to 200-m
included in the ejection head 100 all have the same configuration,
and the head chips 300-1 to 300-m all have the same configuration.
Therefore, when it is not necessary to distinguish the drive signal
selection circuits 200-1 to 200-m, they are simply referred to as
the drive signal selection circuit 200, and the description has
been made that the drive signal selection circuit 200 supplies the
drive signal VOUT to the head chip 300. Then, the description has
been made that the print data signal SI, the clock signal SCK, the
latch signal LAT, the change signal CH, and the drive signals COMA
and COMB are input to the drive signal selection circuit 200.
2. Configuration and Operation of Drive Signal Selection
Circuit
[0053] Next, the configuration and operation of the drive signal
selection circuit 200 will be described. As described above, the
drive signal selection circuit 200 generates a drive signal VOUT by
selecting or not selecting the waveforms of the input drive signals
COMA and COMB, and outputs the drive signal to the corresponding
head chip 300. Therefore, in describing the configuration and
operation of the drive signal selection circuit 200, first, an
example of waveforms of the drive signals COMA and COMB input to
the drive signal selection circuit 200 and an example of a waveform
of the drive signal VOUT output by the drive signal selection
circuit 200 will be described.
[0054] FIG. 2 is a diagram showing an example of waveforms of drive
signals COMA and COMB. As shown in FIG. 2, the drive signal COMA is
a waveform in which a trapezoidal waveform Adp1 arranged in a
period T1 from the rise of the latch signal LAT to the rise of the
change signal CH and a trapezoidal waveform Adp2 arranged in a
period T2 from the rise of the change signal CH to the rise of the
latch signal LAT are continuous. When the trapezoidal waveform Adp1
is supplied to the head chip 300, a small amount of ink is ejected
from the corresponding nozzle of the head chip 300, and when the
trapezoidal waveform Adp2 is supplied to the head chip 300, a
medium amount of ink, more than a small amount, is ejected from the
corresponding nozzle of the head chip 300.
[0055] Further, as shown in FIG. 2, the drive signal COMB is a
waveform in which a trapezoidal waveform Bdp1 arranged in the
period T1 and a trapezoidal waveform Bdp2 arranged in the period T2
are continuous. When the trapezoidal waveform Bdp1 is supplied to
the head chip 300, ink is not ejected from the corresponding nozzle
of the head chip 300. The trapezoidal waveform Bdp1 is a waveform
for slightly vibrating the ink near the opening of the nozzle to
prevent an increase in ink viscosity. Further, when the trapezoidal
waveform Bdp2 is supplied to the head chip 300, a small amount of
ink is ejected from the corresponding nozzle of the head chip 300,
as in the case where the trapezoidal waveform Adp1 is supplied.
[0056] Here, as shown in FIG. 2, the voltage values at the start
timing and end timing of each of the trapezoidal waveforms Adp1,
Adp2, Bdp1, and Bdp2 are all common to a voltage Vc. That is, each
of the trapezoidal waveforms Adp1, Adp2, Bdp1, and Bdp2 is a
waveform that starts at a voltage Vc and ends at a voltage Vc. A
cycle Ta including the period T1 and the period T2 corresponds to a
printing cycle for forming new dots on the medium.
[0057] In FIG. 2, although the trapezoidal waveform Adp1 and the
trapezoidal waveform Bdp2 are shown as having the same waveform,
the trapezoidal waveform Adp1 and the trapezoidal waveform Bdp2 may
have different waveforms. Further, the description has been made
that a small amount of ink is ejected from the corresponding
nozzles in both the case where the trapezoidal waveform Adp1 is
supplied to the head chip 300 and the case where the trapezoidal
waveform Bdp1 is supplied to the head chip 300. However, the
present disclosure is not limited thereto. That is, the waveforms
of the drive signals COMA and COMB are not limited to the example
shown in FIG. 2, and a signal having various combinations of
waveforms may be used depending on the properties of the ink
ejected from the nozzle of the head chip 300, the material of the
medium on which the ink lands, and the like. Further, the drive
signal COMA1 and the drive signal COMA2 may have different
waveforms, and similarly, the drive signal COMB1 and the drive
signal COMB2 may have different waveforms.
[0058] FIG. 3 is a diagram showing an example of a waveform of the
drive signal VOUT corresponding to each of a large dot LD, a medium
dot MD, a small dot SD, and a non-recording ND in the size of the
dots formed on the medium.
[0059] As shown in FIG. 3, the drive signal VOUT when the large dot
LD is formed on the medium is a waveform in which the trapezoidal
waveform Adp1 arranged in the period T1 and the trapezoidal
waveform Adp2 arranged in the period T2 are continuous in the cycle
Ta. When this drive signal VOUT is supplied to the head chip 300, a
small amount of ink and a medium amount of ink are ejected from the
corresponding nozzles. Therefore, in the cycle Ta, each ink lands
on the medium and coalesces, so that the large dot LD is formed on
the medium.
[0060] Further, the drive signal VOUT when the medium dot MD is
formed on the medium is a waveform in which the trapezoidal
waveform Adp1 arranged in the period T1 and the trapezoidal
waveform Bdp2 arranged in the period T2 are continuous in the cycle
Ta. When this drive signal VOUT is supplied to the head chip 300, a
small amount of ink is ejected twice from the corresponding
nozzles. Therefore, in the cycle Ta, each ink lands on the medium
and coalesces, so that the medium dot MD is formed on the
medium.
[0061] The drive signal VOUT when the small dot SD is formed on the
medium is a waveform in which the trapezoidal waveform Adp1
arranged in the period T1 and a constant waveform at the voltage Vc
arranged in the period T2 are continuous in the cycle Ta. When this
drive signal VOUT is supplied to the head chip 300, a small amount
of ink is ejected once from the corresponding nozzle. Therefore, in
the cycle Ta, the ink lands on the medium, and the small dot SD is
formed on the medium.
[0062] The drive signal VOUT corresponding to the non-recording ND
that does not form dots on the medium is a waveform in which the
trapezoidal waveform Bdp1 arranged in the period T1 and a constant
waveform at the voltage Vc arranged in the period T2 are continuous
in the cycle Ta. When this drive signal VOUT is supplied to the
head chip 300, the ink in the vicinity of the opening of the
corresponding nozzle only slightly vibrates, and the ink is not
ejected. Therefore, in the cycle Ta, the ink does not land on the
medium and dots are not formed on the medium.
[0063] Here, the constant waveform at the voltage Vc is the voltage
supplied to the head chip 300 when none of the trapezoidal
waveforms Adp1, Adp2, Bdp1, and Bdp2 is selected as the drive
signal VOUT, and specifically, is a waveform of a voltage value in
which a voltage Vc immediately before the trapezoidal waveforms
Adp1, Adp2, Bdp1, and Bdp2 is held in the head chip 300. Therefore,
when none of the trapezoidal waveforms Adp1, Adp2, Bdp1, and Bdp2
is selected as the drive signal VOUT, the voltage Vc is supplied to
the head chip 300 as the drive signal VOUT.
[0064] Next, the configuration and operation of the drive signal
selection circuit 200 will be described. FIG. 4 is a diagram
showing the configuration of the drive signal selection circuit
200. As shown in FIG. 4, the drive signal selection circuit 200
includes a selection control circuit 210 and a plurality of
selection circuits 230. Further, FIG. 4 shows an example of the
head chip 300 to which the drive signal VOUT output from the drive
signal selection circuit 200 is supplied. As shown in FIG. 4, the
head chip 300 includes p ejection portions 600 each having a
piezoelectric element 60.
[0065] The print data signal SI, the latch signal LAT, the change
signal CH, and the clock signal SCK are input to the selection
control circuit 210. The selection control circuit 210 is provided
with a set of a shift register (S/R) 212, a latch circuit 214, and
a decoder 216 corresponding to each of the p ejection portions 600
included in the head chip 300. That is, the drive signal selection
circuit 200 includes a set of the same number of shift registers
212, latch circuits 214, and decoders 216 as the p ejection
portions 600 included in the head chip 300.
[0066] The print data signal SI is a signal synchronized with the
clock signal SCK, and a signal having a total of 2p bits including
2-bit print data [SIH, SIL] for selecting one of large dot LD,
medium dot MD, small dot SD, and non-recording ND with respect to
each of the p ejection portions 600. The input print data signal SI
is held in the shift register 212 for each of the two bits of print
data [SIH, SIL] included in the print data signal SI, corresponding
to the p ejection portions 600. Specifically, in the selection
control circuit 210, the p-th stage shift registers 212
corresponding to the p ejection portions 600 are vertically coupled
to each other, and the print data [SIH, SIL] serially input as the
print data signal SI is sequentially transferred to the subsequent
stage according to the clock signal SCK. In FIG. 4, in order to
distinguish the shift register 212, the shift register 212 to which
the print data signal SI is input is described as a first stage, a
second stage, . . . , a p-th stage in order from the upstream.
[0067] Each of the p latch circuits 214 latches the 2-bit print
data [SIH, SIL] held by each of the p shift registers 212 at the
rising edge of the latch signal LAT.
[0068] FIG. 5 is a diagram showing the decoding contents in the
decoder 216. The decoder 216 outputs the selection signals S1 and
S2 according to the latched 2-bit print data [SIH, SIL]. For
example, when the 2-bit print data [SIH, SIL] is [1,0], the decoder
216 outputs the logic level of the selection signal S1 as H and L
levels in the periods T1 and T2, and outputs the logic level of the
selection signal S2 as L and H levels in the periods T1 and T2 to
the selection circuit 230.
[0069] The selection circuit 230 is provided corresponding to each
of the ejection portions 600. That is, the number of selection
circuits 230 included in the drive signal selection circuit 200 is
p, which is the same as the number of ejection portions 600
included in the corresponding head chip 300. FIG. 6 is a diagram
showing a configuration of a selection circuit 230 corresponding to
one ejection portion 600. As shown in FIG. 6, the selection circuit
230 has inverters 232a and 232b, which are NOT circuits, and
transfer gates 234a and 234b.
[0070] The selection signal S1 is input to the positive control end
not marked with a circle at the transfer gate 234a, while being
logically inverted by the inverter 232a and input to the negative
control end marked with a circle at the transfer gate 234a.
Further, the drive signal COMA is supplied to the input end of the
transfer gate 234a. The selection signal S2 is input to the
positive control end not marked with a circle at the transfer gate
234b, while being logically inverted by the inverter 232b and input
to the negative control end marked with a circle at the transfer
gate 234b. Further, the drive signal COMB is supplied to the input
end of the transfer gate 234b. The output ends of the transfer
gates 234a and 234b are commonly coupled, and the drive signal VOUT
is output from the output ends.
[0071] Specifically, the transfer gate 234a makes between the input
end and the output end conductive when the selection signal S1 is H
level, and makes between the input end and the output end
non-conductive when the selection signal S1 is L level. Further,
the transfer gate 234b makes between the input end and the output
end conductive when the selection signal S2 is H level, and makes
between the input end and the output end non-conductive when the
selection signal S2 is L level. That is, the selection circuit 230
selects the waveforms of the drive signals COMA and COMB based on
the input selection signals S1 and S2, and outputs the drive signal
VOUT of the selected waveform.
[0072] The operation of the drive signal selection circuit 200 will
be described with reference to FIG. 7. FIG. 7 is a diagram for
describing the operation of the drive signal selection circuit 200.
The print data [SIH, SIL] included in the print data signal SI is
serially input in synchronization with the clock signal SCK, and is
sequentially transferred in the shift register 212 corresponding to
the ejection portion 600. When the input of the clock signal SCK is
stopped, the 2-bit print data [SIH, SIL] corresponding to each of
the p ejection portions 600 is held in each shift register 212. The
print data [SIH, SIL] included in the print data signal SI is input
in the order corresponding to the p-th stage, . . . , second stage,
and first stage ejection portion 600 of the shift register 212.
[0073] When the latch signal LAT rises, each of the latch circuits
214 latches the 2-bit print data [SIH, SIL] held in the shift
register 212 all at once. In FIG. 7, LT1, LT2, . . . , LTp
represent 2-bit print data [SIH, SIL] latched by the latch circuit
214 corresponding to the shift register 212 of the first stage, the
second stage, . . . , and the p-th stage.
[0074] The decoder 216 outputs the logic levels of the selection
signals S1 and S2 as the contents shown in FIG. 5 in each of the
periods T1 and T2 depending on the dot size defined by the latched
2-bit print data [SIH, SIL].
[0075] Specifically, when the input print data [SIH, SIL] is [1,1],
the decoder 216 sets the selection signal S1 to H and H levels in
the periods T1 and T2, and sets the selection signal S2 to L and L
levels in the periods T1 and T2. In this case, the selection
circuit 230 selects the trapezoidal waveform Adp1 in the period T1
and selects the trapezoidal waveform Adp2 in the period T2. As a
result, the drive signal VOUT corresponding to the large dot LD
shown in FIG. 3 is generated.
[0076] When the input print data [SIH, SIL] is [1,0], the decoder
216 sets the selection signal S1 to H and L levels in the periods
T1 and T2, and sets the selection signal S2 to L and H levels in
the periods T1 and T2. In this case, the selection circuit 230
selects the trapezoidal waveform Adp1 in the period T1 and selects
the trapezoidal waveform Bdp2 in the period T2. As a result, the
drive signal VOUT corresponding to the medium dot MD shown in FIG.
3 is generated.
[0077] When the input print data [SIH, SIL] is [0,1], the decoder
216 sets the selection signal S1 to H and L levels in the periods
T1 and T2, and sets the selection signal S2 to L and L levels in
the periods T1 and T2. In this case, the selection circuit 230
selects the trapezoidal waveform Adp1 in the period T1 and does not
select either the trapezoidal waveform Adp2 or Bdp2 in the period
T2. As a result, the drive signal VOUT corresponding to the small
dot SD shown in FIG. 3 is generated.
[0078] When the input print data [SIH, SIL] is [0,0], the decoder
216 sets the selection signal S1 to L and L levels in the periods
T1 and T2, and sets the selection signal S2 to H and L levels in
the periods T1 and T2. In this case, the selection circuit 230
selects the trapezoidal waveform Bdp1 in the period T1 and does not
select either the trapezoidal waveform Adp2 or Bdp2 in the period
T2. As a result, the drive signal VOUT corresponding to the
non-recording ND shown in FIG. 3 is generated.
[0079] As described above, the drive signal selection circuit 200
selects the waveforms of the drive signals COMA and COMB based on
the print data signal SI, the latch signal LAT, the change signal
CH, and the clock signal SCK, and outputs the waveforms as the
drive signal VOUT. Then, the drive signal selection circuit 200
selects or does not select the waveforms of the drive signals COMA
and COMB, thereby controlling the size of the dots formed on the
medium, and as a result, in the liquid ejecting apparatus 1, dots
of a desired size are formed on the medium.
[0080] Here, the drive signals COMA and COMB output by the drive
signal output unit 50 are examples of drive signals. Further,
considering that the drive signal selection circuit 200 generates
the drive signal VOUT by selecting or not selecting the waveforms
included in the drive signals COMA and COMB, the drive signal VOUT
is also an example of the drive signal.
3. Configuration of Drive Circuit
[0081] Next, the configurations of the drive circuits 51a and 51b
included in the drive signal output unit 50 will be described. The
drive circuit 51a and the drive circuit 51b have the same
configuration except that the input signal and the output signal
are different. Therefore, in the following description, the
configuration will be described by taking as an example the drive
circuit 51a in which the basic drive data dA is input and the drive
signal COMA is output, and the description of the configuration of
the drive circuit 51b will be omitted.
[0082] FIG. 8 is a diagram showing a configuration of the drive
circuit 51a. The drive circuit 51a includes a digital to analog
converter (DAC) 510 that converts the basic drive data dA, that is
a digital signal which is the basis of the drive signal COMA, into
a basic drive signal aA that is an analog signal, and an output
circuit 550 that amplifies a signal based on the basic drive signal
aA and generates the drive signal COMA.
[0083] As shown in FIG. 8, the drive circuit 51a includes an
integrated circuit 500, an output circuit 550, and a plurality of
circuit elements. The integrated circuit 500 outputs gate drive
signals Hgd and Lgd for driving transistors M1 and M2 included in
an amplifier circuit 570 of the output circuit 550 based on the
input basic drive data dA. The integrated circuit 500 includes a
DAC 510, a modulation circuit 520 and a gate drive circuit 530.
[0084] The basic drive data dA is input to the DAC 510. The DAC 510
generates the basic drive signal aA of the analog signal by
digital-to-analog converting the basic drive data dA. The signal
obtained by amplifying the voltage of the basic drive signal aA
becomes the drive signal COMA. That is, the basic drive signal aA
is a target signal before amplification of the drive signal COMA
defined by the basic drive data dA of the digital signal.
[0085] The modulation circuit 520 includes a comparator 521 and an
inverter 522. The basic drive signal aA is input to the comparator
521. The comparator 521 outputs a modulation signal Ms that becomes
H level when the voltage value of the basic drive signal aA rises
and becomes a predetermined voltage threshold Vth1 or more, and
that becomes L level when the voltage value of the basic drive
signal aA decreases and falls below a predetermined voltage
threshold Vth2.
[0086] The modulation signal Ms output from the comparator 521 is
branched in the modulation circuit 520. One of the branched
modulation signals Ms is output to the gate drive circuit 530 as a
modulation signal Ms1. Further, the other of branched modulation
signals Ms is output to the gate drive circuit 530 as a modulation
signal Ms2 via the inverter 522. That is, the modulation circuit
520 generates two modulation signals Ms1 and Ms2 having exclusive
logic levels and outputs the modulation signals to the gate drive
circuit 530. Here, the two signals having exclusive logic levels
include signals whose timing is controlled by a delay circuit (not
shown) or the like so that the logic levels of each other's signals
do not become H level at the same time. That is, the two signals of
the exclusive logic levels include signals that do not become H
level at the same time.
[0087] The gate drive circuit 530 includes gate drivers 531 and
532. The gate driver 531 generates a gate drive signal Hgd by
level-shifting the voltage value of the modulation signal Ms1
output from the modulation circuit 520, and outputs the gate drive
signal from a terminal Hdr. Specifically, of the power supply
voltage of the gate driver 531, a voltage is supplied to the high
potential side via a terminal Bst, and a voltage is supplied to the
low potential side via a terminal Sw. The terminal Bst is commonly
coupled to one end of a capacitor C5 provided outside the
integrated circuit 500 and the cathode terminal of a diode Dl for
preventing backflow. Further, the other end of the capacitor C5 is
coupled to the terminal Sw. Further, the anode terminal of the
diode Dl is coupled to a terminal Gvd. A voltage GVDD of the
predetermined voltage value described above is supplied to the
terminal Gvd. Therefore, the potential difference between the
terminal Bst and the terminal Sw is approximately equal to the
potential difference between both ends of the capacitor C5, that
is, the voltage GVDD. The gate driver 531 generates a gate drive
signal Hgd whose voltage value is larger than that of the terminal
Sw by the voltage GVDD according to the input modulation signal
Ms1, and outputs the gate drive signal from the terminal Hdr.
[0088] The gate driver 532 operates on the lower potential side
than the gate driver 531. The gate driver 532 generates a gate
drive signal Lgd by level-shifting the voltage value of the
modulation signal Ms2 output from the modulation circuit 520, and
outputs the gate drive signal from a terminal Ldr. Specifically, of
the power supply voltage of the gate driver 532, a voltage GVDD is
supplied to the high potential side, and a ground signal is
supplied to the low potential side. The gate driver 532 generates a
gate drive signal Lgd whose voltage value is larger than that of
the terminal Gnd by the voltage GVDD according to the input
modulation signal Ms2, and outputs the gate drive signal from the
terminal Ldr.
[0089] Here, the voltage GVDD is generated, for example, by
boosting the voltage VDD. Specifically, the voltage GVDD is a
voltage whose voltage value is larger than a gate drive threshold
voltage of the transistors M1 and M2 included in the amplifier
circuit 570 to be described later, and is generated by boosting the
voltage VDD so as to be, for example, DC 7.5 V.
[0090] The output circuit 550 includes an amplifier circuit 570 and
a smoothing circuit 560. Further, the amplifier circuit 570 has
transistors M1 and M2. Each of the transistors M1 and M2 shown in
FIG. 8 may be, for example, a surface mount type N-channel type
field effect transistor (FET).
[0091] A voltage VHV is supplied to the drain electrode of the
transistor M1. Further, the gate electrode of the transistor M1 is
coupled to one end of a resistor R1. The other end of the resistor
R1 is coupled to the terminal Hdr. Further, the source electrode of
the transistor M1 is coupled to the terminal Sw. The transistor M1
coupled as described above operates according to the gate drive
signal Hgd output from the terminal Hdr.
[0092] The drain electrode of the transistor M2 is coupled to the
source electrode of the transistor M1. Further, the gate electrode
of the transistor M2 is coupled to one end of a resistor R2. The
other end of the resistor R2 is coupled to the terminal Ldr.
Further, a ground signal is supplied to the source electrode of the
transistor M2. The transistor M2 coupled as described above
operates according to the gate drive signal Lgd output from the
terminal Ldr.
[0093] In the amplifier circuit 570 configured as described above,
when the transistor M1 is controlled to be off and the transistor
M2 is controlled to be on, the coupling point to which the terminal
Sw is coupled becomes a ground potential. Therefore, the voltage
GVDD is supplied to the terminal Bst. On the other hand, when the
transistor M1 is controlled to be on and the transistor M2 is
controlled to be off, the voltage VHV is supplied to the coupling
point to which the terminal Sw is coupled. Therefore, the voltage
VHV+voltage GVDD is supplied to the terminal Bst.
[0094] Here, the gate driver 531 that drives the transistor M1
drives the capacitor C5 as a floating power supply. Then, in
response to the operation of the transistors M1 and M2, the voltage
of the terminal Sw to which one end of the capacitor C5 is coupled
changes to the ground potential or the voltage VHV, so that the
gate driver 531 generates a gate drive signal Hgd having L level of
voltage VHV and H level of voltage VHV+voltage GVDD, and supplies
the gate drive signal to the gate electrode of the transistor M1.
The transistor M1 performs a switching operation based on the gate
drive signal Hgd supplied to the gate electrode. Further, the gate
driver 532 that drives the transistor M2 generates a gate drive
signal Lgd having L level of the ground potential and H level of
the voltage GVDD, regardless of the operation of the transistors M1
and M2, and supplies the gate drive signal to the gate electrode of
the transistor M2. The transistor M2 performs a switching operation
based on the gate drive signal Lgd supplied to the gate
electrode.
[0095] Thereby, an amplified modulation signal Msa obtained by
amplifying the modulation signal Ms based on the voltage VHV is
generated at the coupling point between the source electrode of the
transistor M1 and the drain electrode of the transistor M2.
[0096] The smoothing circuit 560 includes a coil L1 and a capacitor
C1. One end of the coil L1 is commonly coupled to the source
electrode of the transistor M1 and the drain electrode of the
transistor M2. Further, the other end of the coil L1 is commonly
coupled to a terminal Out from which the drive signal COMA is
output and one end of the capacitor C1. Further, a ground signal is
supplied to the other end of the capacitor C1. That is, the
smoothing circuit 560 constitutes a low-pass filter circuit with
the coil L1 and the capacitor C1. The smoothing circuit 560 coupled
as described above smoothes the amplified modulation signal Msa
supplied to the coupling point between the transistors M1 and M2.
Thereby, the amplified modulation signal Msa is demodulated and the
drive signal COMA is generated. Then, the generated drive signal
COMA is output from the terminal Out.
[0097] Although not shown in FIG. 8, the drive circuit 51a may
include a feedback circuit that feeds back the output drive signal
COMA. As a result, the operating characteristics of the drive
circuit 51 are stabilized, and the possibility of waveform
distortion occurring in the drive signal COMA output by the drive
circuit 51a can be reduced.
[0098] Here, the DAC 510 that generates and outputs the basic drive
signal aA of the analog signal by digital/analog conversion of the
basic drive data dA is an example of a D/A converter, and the
output circuit 550 is an example of a drive signal output
circuit.
4. Structure of Liquid Ejecting Apparatus
[0099] Next, the schematic structure of the liquid ejecting
apparatus 1 will be described. FIG. 9 is an explanatory diagram
showing a schematic structure of the liquid ejecting apparatus 1.
FIG. 9 shows arrows indicating the X direction, the Y direction,
and the Z direction that are orthogonal to each other. The Y
direction corresponds to the direction in which the medium P is
transported, the X direction is a direction orthogonal to the Y
direction and parallel to the horizontal plane and corresponds to
the main scanning direction, and the Z direction is the up-and-down
direction of the liquid ejecting apparatus 1 and corresponds to the
vertical direction. Here, in the following description, when the
orientations of the X direction, the Y direction, and the Z
direction are specified, in some cases, the tip end side of the
arrow indicating the X direction is referred to as a +X side, and
the starting point side thereof is referred to as a -X side, the
tip end side of the arrow indicating the Y direction is referred to
as a +Y side, and the starting point side thereof is referred to as
a -Y side, and the tip end side of the arrow indicating the Z
direction is referred to as a +Z side, and the starting point side
thereof is referred to as a -Z side.
[0100] As shown in FIG. 9, the liquid ejecting apparatus 1 includes
a liquid container 5, a pump 8, and a transport mechanism 40 in
addition to the control unit 10 and the head unit 20 described
above. Here, although not shown in FIG. 9, the drive signal output
unit 50 is located on the -Z side of the head unit 20. In the
following description, a case where the head unit 20 has six
ejection heads 100 will be exemplified and described.
[0101] As described above, the control unit 10 includes the main
control circuit 11 and the power supply voltage generation circuit
12, and controls the operation of the liquid ejecting apparatus 1
including the head unit 20. Further, the control unit 10 may
include an interface circuit or the like for communicating with a
storage circuit for storing various information and a host computer
provided outside the liquid ejecting apparatus 1 in addition to the
main control circuit 11 and the power supply voltage generation
circuit 12.
[0102] The control unit 10 receives an image signal input from a
host computer or the like provided outside the liquid ejecting
apparatus 1, performs predetermined image processing on the
received image signal, and then outputs the image-processed signal
to the head unit 20 as an image information signal IP. Further, the
control unit 10 controls the transport of the medium P by
outputting a transport control signal TC to the transport mechanism
40 that transports the medium P, and controls the operation of the
pump 8 by outputting a pump control signal AC to the pump 8.
[0103] The liquid container 5 stores ink to be ejected to the
medium P. Specifically, the liquid container 5 includes four
containers in which four color inks of cyan C, magenta M, yellow Y,
and black K are individually stored. The ink stored in the liquid
container 5 is supplied to the head unit 20 via a tube or the like.
The container in which the ink contained in the liquid container 5
is stored is not limited to four, and may include a container in
which inks of colors other than cyan C, magenta M, yellow Y, and
black K are stored, and include a plurality of containers of any
one of cyan C, magenta M, yellow Y, and black K.
[0104] The head unit 20 includes ejection heads 100-1 to 100-6
arranged side by side in the X direction. The ejection heads 100-1
to 100-6 included in the head unit 20 are arranged side by side in
the order of the ejection head 100-1, the ejection head 100-2, and
the ejection head 100-3, the ejection head 100-4, the ejection head
100-5, and the ejection head 100-6 from the -X side to the +X side
so as to be equal to or larger than the width of the medium P along
the X direction. The head unit 20 distributes the ink supplied from
the liquid container 5 to each of the ejection heads 100-1 to
100-6, and operates based on the image information signal IP input
from the control unit 10 and the drive signals COMA and COMB output
by the drive signal output unit 50, respectively, of the ejection
heads 100-1 to 100-6. Thus, the ink supplied from the liquid
container 5 is ejected from each of the ejection heads 100-1 to
100-6 toward the medium P.
[0105] The transport mechanism 40 transports the medium P along the
Y direction based on the transport control signal TC input from the
control unit 10. Such a transport mechanism 40 includes, for
example, a roller (not shown) for transporting the medium P, a
motor for rotating the roller, and the like.
[0106] The pump 8 controls whether or not to supply air A to the
head unit 20 and the amount of the air A supplied to the head unit
20 based on the pump control signal AC input from the control unit
10. The pump 8 is coupled to the head unit 20 via, for example, two
tubes. The pump 8 controls the opening and closing of the valve of
the head unit 20 by controlling the air A flowing through each
tube.
[0107] As described above, in the liquid ejecting apparatus 1, the
control unit 10 generates an image information signal IP based on
the image signal input from the host computer or the like, controls
the operation of the head unit 20 by the generated image
information signal IP, and controls the transport of the medium P
in the transport mechanism 40 by the transport control signal TC.
Thereby, the liquid ejecting apparatus 1 can land the ink at a
desired position on the medium P, and thus can form a desired image
on the medium P.
5. Structure of Head Unit
[0108] Next, the structures of the head unit 20 and the drive
signal output unit 50 will be described. FIG. 10 is an exploded
perspective view of the head unit 20 and the drive signal output
unit 50 when viewed from the -Z side, and FIG. 11 is an exploded
perspective view of the head unit 20 and the drive signal output
unit 50 when viewed from the +Z side.
[0109] As shown in FIGS. 10 and 11, the head unit 20 includes a
flow path structure G1 that introduces ink from the liquid
container 5, a supply control portion G2 that controls the supply
of the introduced ink into the ejection head 100, a liquid ejection
portion G3 having the ejection head 100 for ejecting the supplied
ink, and an ejection control portion G4 that controls the ejection
of ink from the ejection head 100. Then, the flow path structure
G1, the supply control portion G2, the liquid ejection portion G3,
and the ejection control portion G4 are laminated in the order of
the ejection control portion G4, the flow path structure G1, the
supply control portion G2, and the liquid ejection portion G3 from
the -Z side to the +Z side along the Z direction in the head unit
20, and are fixed to each other by a fixing means (not shown).
[0110] As shown in FIGS. 10 and 11, the flow path structure G1 has
a plurality of liquid introduction ports SI1 according to the type
of ink supplied to the head unit 20, the number of ink types, and a
plurality of liquid discharge ports DI1 according to the type of
ink and the number of ejection heads 100. The plurality of liquid
introduction ports SI1 are located on the -Z side surface of the
flow path structure G1 and are coupled to the liquid container 5
via a tube (not shown) or the like. Further, the plurality of
liquid discharge ports DI1 are located on the +Z side surface of
the flow path structure G1. An ink flow path that communicates one
liquid introduction port SI1 and a plurality of liquid discharge
ports DI1 corresponding to the liquid introduction port SI1 is
formed inside the flow path structure G1.
[0111] Further, the flow path structure G1 is provided with a
plurality of air introduction ports SA1 and a plurality of air
discharge ports DA1. The plurality of air introduction ports SA1
are provided on the -Z side surface of the flow path structure G1,
and are coupled to the pump 8 via a tube (not shown). Further, the
plurality of air discharge ports DA1 are provided on the +Z side
surface of the flow path structure G1. An air flow path that
communicates one air introduction port SA1 and a plurality of air
discharge ports DA1 corresponding to the air introduction port SA1
is formed inside the flow path structure G1.
[0112] As shown in FIGS. 10 and 11, the supply control portion G2
has a plurality of pressure adjusting units U2 according to the
number of ejection heads 100. Further, each of the plurality of
pressure adjusting units U2 has a plurality of liquid introduction
ports SI2 according to the type of ink supplied to the head unit
20, a plurality of liquid discharge ports DI2 according to the type
of ink supplied to the head unit 20, and a plurality of air
introduction ports SA2 according to the number of tubes coupled to
the pump 8.
[0113] The plurality of liquid introduction ports SI2 are located
on the -Z side of the pressure adjusting unit U2 and are coupled to
the plurality of liquid discharge ports DI1 included in the flow
path structure G1 on a one-to-one basis. That is, the supply
control portion G2 has a liquid introduction port SI2 corresponding
to each of the liquid discharge ports DI1 included in the flow path
structure G1. Further, the plurality of liquid discharge ports DI2
are located on the -Z side of the pressure adjusting unit U2. An
ink flow path that communicates one liquid introduction port S12
and one liquid discharge port DI2 is formed inside the pressure
adjusting unit U2.
[0114] The plurality of air introduction ports SA2 are located on
the -Z side of the pressure adjusting unit U2 and are coupled to
the plurality of air discharge ports DA1 included in the flow path
structure G1 on a one-to-one basis. That is, the supply control
portion G2 has an air introduction port SA2 corresponding to each
of the air discharge port DA1 included in the flow path structure
G1. Further, inside each of the pressure adjusting units U2, a
supply control means (not shown) for controlling the supply of ink
to the ejection head 100 is provided, including a valve for opening
and closing the ink flow path, a valve for adjusting the pressure
of the ink flowing through the ink flow path, and the like. An air
flow path coupling one air introduction port SA2 and one supply
control means is formed inside the pressure adjusting unit U2.
[0115] The pressure adjusting unit U2 configured as described above
controls the operation of the valve included in the supply control
means based on the air A supplied via the air flow path formed
inside, thereby controlling the amount of ink flowing in the ink
flow path formed inside the pressure adjusting unit U2.
[0116] As shown in FIGS. 10 and 11, the liquid ejection portion G3
has ejection heads 100-1 to 100-6 and a support member 35. Each of
the ejection heads 100-1 to 100-6 is located on the +Z side of the
support member 35. The ejection heads 100-1 to 100-6 are fixed to
the support member 35 by a fixing means such as screws.
[0117] A plurality of liquid introduction ports SI3 are located on
the -Z side of each of the ejection heads 100-1 to 100-6. Further,
the support member 35 is formed with openings corresponding to the
plurality of liquid introduction ports SI3. Then, by inserting the
corresponding openings formed in the support member 35 through each
of the plurality of liquid introduction ports SI3, each of the
plurality of liquid introduction ports SI3 is exposed on the -Z
side of the liquid ejection portion G3. The plurality of liquid
introduction ports SI3 exposed on the -Z side of the liquid
ejection portion G3 are coupled to the plurality of liquid
discharge ports DI2 included in the supply control portion G2 on a
one-to-one basis. That is, the liquid ejection portion G3 has a
liquid introduction port SI3 corresponding to each of the liquid
discharge ports DI2 included in the supply control portion G2.
[0118] Here, the flow of ink until the ink supplied from the liquid
container 5 reaches the ejection head 100 will be described. The
ink stored in the liquid container 5 is first supplied to the
plurality of liquid introduction ports SI1 included in the flow
path structure G1 via a tube (not shown) or the like. The ink
supplied to the plurality of liquid introduction ports SI1 is
distributed by an ink flow path (not shown) provided inside the
flow path structure G1, and then supplied to the liquid
introduction port SI2 included in the pressure adjusting unit U2
via the liquid discharge port DI1. The ink supplied to the liquid
introduction port SI2 is supplied to the liquid introduction port
SI3 included in each of the ejection heads 100-1 to 100-6 included
in the liquid ejection portion G3 via the ink flow path provided
inside the pressure adjusting unit U2 and the liquid discharge port
DI2. That is, the flow path structure G1 functions as a
distribution flow path member that distributes and supplies ink to
each of the plurality of ejection heads 100 included in the head
unit 20, and ink whose flow rate and pressure have been adjusted by
the pressure adjusting unit U2 included in the supply control
portion G2 is supplied to the ejection heads 100-1 to 100-6
included in the liquid ejection portion G3.
[0119] Here, an example of the arrangement of the ejection heads
100-1 to 100-6 in the head unit 20 will be described. FIG. 12 is a
bottom view of the head unit 20 when viewed from the +Z side. As
shown in FIG. 12, each of the ejection heads 100-1 to 100-6
included in the head unit 20 has six head chips 300 arranged side
by side in the X direction. Each head chip 300 has a plurality of
nozzles N for ejecting ink. The plurality of nozzles N included in
each of the head chips 300 are arranged side by side along a row
direction RD different from the X direction and the Y direction in
a plane perpendicular to the Z direction and formed by the X
direction and the Y direction. Here, in the following description,
a plurality of nozzles N arranged side by side along the row
direction RD may be referred to as a nozzle row.
[0120] Here, FIG. 12 shows a case where the head chip 300 has two
rows of nozzle rows along the row direction RD, but the nozzle rows
of the ejection head 100 are not limited to two rows. Further, FIG.
12 shows a case where each of the ejection heads 100-1 to 100-6 has
six head chips 300, but the number of head chips 300 included in
each of the ejection heads 100-1 to 100-6 may be two or more, and
is not limited to six.
[0121] Next, a structure of the ejection head 100 will be
described. FIG. 13 is an exploded perspective view showing a
structure of the ejection head 100. The ejection head 100 includes
a filter portion 110, a seal member 120, a wiring substrate 130, a
holder 140, six head chips 300, and a fixing plate 150. The
ejection head 100 is configured by superimposing the filter portion
110, the seal member 120, the wiring substrate 130, the holder 140,
and the fixing plate 150 in this order from the -Z side to the +Z
side along the Z direction, and six head chips 300 are accommodated
between the holder 140 and the fixing plate 150.
[0122] The filter portion 110 has a substantially parallelogram
shape in which two opposite sides extend along the X direction and
two opposite sides extend along the row direction RD. The filter
portion 110 includes a plurality of liquid introduction ports SI3
and a plurality of filters 113 corresponding to each of the
plurality of liquid introduction ports SI3. The filter 113 collects
air bubbles and foreign substances contained in the ink supplied
from each of the liquid introduction ports SI3.
[0123] The seal member 120 is located on the +Z side of the filter
portion 110, and has a substantially parallelogram shape in which
two opposite sides extend along the X direction and two opposite
sides extend along the row direction RD. Through-holes 125 through
which the ink supplied from the filter portion 110 flows are
provided at the four corners of the seal member 120. Such a seal
member 120 is formed of, for example, an elastic member such as
rubber. The seal member 120 allows liquid-tight communication
between a liquid discharge hole (not shown) that communicates with
the liquid introduction port SI3 via the filter 113 formed on the
+Z side surface of the filter portion 110, and a liquid
introduction port 145 of the holder 140, which will be described
later.
[0124] The wiring substrate 130 is located on the +Z side of the
seal member 120, and has a substantially parallelogram shape in
which two opposite sides extend along the X direction and two
opposite sides extend along the row direction RD. Notches 135 are
formed at the four corners of the wiring substrate 130. An ink flow
path formed between a liquid discharge hole (not shown)
communicating with the liquid introduction port SI3 and a liquid
introduction port 145 of the holder 140, which will be described
later, which is communicated with the through-hole 125 of the seal
member 120, is located in the notch 135. The wiring substrate 130
is formed with wiring for propagating various signals such as the
drive signals COMA and COMB and the voltage VHV supplied to the
ejection head 100.
[0125] The holder 140 is located on the +Z side of the wiring
substrate 130, and has a substantially parallelogram shape in which
two opposite sides extend along the X direction and two opposite
sides extend along the row direction RD. The holder 140 has holder
members 141, 142, and 143. The holder members 141, 142, and 143 are
laminated in the order of the holder member 141, the holder member
142, and the holder member 143 from the -Z side to the +Z side
along the Z direction.
[0126] Inside the holder member 143, an opening is provided on the
+Z side, and an accommodation space (not shown) for accommodating
the head chip 300 is formed. Six head chips 300 are accommodated in
the accommodation space formed inside the holder member 143.
Further, the holder 140 is provided with slit holes 146
corresponding to each of the six head chips 300. A flexible wiring
substrate 346 for propagating various signals such as the drive
signals COMA and COMB and the voltage VHV to the head chip 300 is
inserted into the slit hole 146. Accordingly, various signals such
as the drive signals COMA and COMB and the voltage VHV are supplied
to the six head chips 300 accommodated in the accommodation space
formed inside the holder member 143. The accommodation space formed
inside the holder member 143 may be six spaces corresponding to the
six head chips 300, or one space commonly provided in the six head
chips 300.
[0127] Further, four liquid introduction ports 145 are provided at
the four corners of the upper surface of the holder 140. As
described above, each of the liquid introduction ports 145 is
coupled to the through-hole 125 provided in the seal member 120.
Accordingly, ink is supplied to the liquid introduction port 145.
Then, the ink introduced into the liquid introduction port 145 is
distributed to the six head chips 300 by the ink flow path provided
inside the holder 140.
[0128] The fixing plate 150 is located on the +Z side of the holder
140 and seals the accommodation space formed inside the holder
member 143. The fixing plate 150 has a flat surface portion 151 and
bent portions 152, 153, and 154. The flat surface portion 151 has a
substantially parallelogram shape in which two opposite sides
extend along the X direction and two opposite sides extend along
the row direction RD. The flat surface portion 151 has six openings
155 corresponding to the head chip 300. The six head chips 300 are
fixed to the holder member 143 of the holder 140 and are also fixed
to the flat surface portion 151 so that two rows of nozzle rows are
exposed via the corresponding openings 155 formed in the flat
surface portion 151.
[0129] The bent portion 152 is a member that is coupled to one side
extending along the X direction of the flat surface portion 151 and
is integrated with the flat surface portion 151 bent to the -Z
side, the bent portion 153 is a member that is coupled to one side
extending along the row direction RD of the flat surface portion
151 and is integrated with the flat surface portion 151 bent to the
-Z side, and the bent portion 154 is a member that is coupled to
the other side extending along the row direction RD of the flat
surface portion 151 and is integrated with the flat surface portion
151 bent to the -Z side.
[0130] Next, an example of the structure of the head chip 300 will
be described. FIG. 14 is a diagram showing a schematic structure of
the head chip 300, and is a cross-sectional view when the head chip
300 is cut in a direction perpendicular to the row direction RD so
as to include at least one nozzle N. As shown in FIG. 14, the head
chip 300 has a nozzle plate 310 provided with a plurality of
nozzles N that eject ink, a flow path forming substrate 321 that
defines a communication flow path 355, an individual flow path 353,
and a reservoir R, a pressure chamber substrate 322 that defines a
pressure chamber C, a protective substrate 323, a compliance
portion 330, a diaphragm 340, a piezoelectric element 60, a
flexible wiring substrate 346, and a case 324 that defines the
reservoir R and the liquid introduction port 351. Ink is supplied
to the head chip 300 from a liquid discharge port (not shown)
provided in the holder 140 via the liquid introduction port 351.
The ink supplied to the head chip 300 reaches the nozzle N via the
ink flow path 350 configured including the reservoir R, the
individual flow path 353, the pressure chamber C, and the
communication flow path 355, and the piezoelectric element 60 is
driven to eject the ink from the nozzle N. Here, a configuration
including the piezoelectric element 60, the diaphragm 340, the
nozzle N, the individual flow path 353, the pressure chamber C, and
the communication flow path 355 to eject ink may be referred to as
the ejection portion 600.
[0131] The structure of the head chip 300 will be specifically
described. The ink flow path 350 is configured by laminating a flow
path forming substrate 321, a pressure chamber substrate 322, and a
case 324 along the Z direction. The ink introduced into the case
324 from the liquid introduction port 351 is stored in the
reservoir R. The reservoir R is a common flow path communicating
with a plurality of individual flow paths 353 corresponding to each
of the plurality of nozzles N constituting the nozzle row.
[0132] The ink stored in the reservoir R is supplied to the
pressure chamber C via the individual flow path 353. In the
pressure chamber C, by applying pressure to the stored ink, the ink
is ejected from the nozzle N via the communication flow path 355.
The diaphragm 340 is located on the -Z side of the pressure chamber
C so as to seal the pressure chamber C, and the piezoelectric
element 60 is located on the -Z side of the diaphragm 340.
[0133] The piezoelectric element 60 is constituted by a
piezoelectric body and a pair of electrodes formed on both sides of
the piezoelectric body. When the drive signal VOUT is supplied to
one of the pair of electrodes included in the piezoelectric element
60 via the flexible wiring substrate 346 and the reference voltage
signal VBS is supplied to the other of the pair of electrodes
included in the piezoelectric element 60 via the flexible wiring
substrate 346, the piezoelectric body is displaced by the potential
difference generated between the pair of electrodes, and as a
result, the piezoelectric element 60 including the piezoelectric
body is driven. As the piezoelectric element 60 is driven, the
diaphragm 340 provided with the piezoelectric element 60 is
deformed, and as a result, the internal pressure of the pressure
chamber C changes. Then, as the internal pressure of the pressure
chamber C changes, the ink stored in the pressure chamber C is
ejected from the nozzle N via the communication flow path 355.
[0134] Further, the nozzle plate 310 and the compliance portion 330
are fixed to the +Z side of the flow path forming substrate 321.
The nozzle plate 310 is located on the +Z side of the communication
flow path 355. A plurality of nozzles N are arranged side by side
on the nozzle plate 310 along the row direction RD. The compliance
portion 330 is located on the +Z side of the reservoir R and the
individual flow path 353, and includes a sealing film 331 and a
support 332. The sealing film 331 is a flexible film-like member,
and seals the +Z side of the reservoir R and the individual flow
path 353. The outer peripheral edge of the sealing film 331 is
supported by a frame-shaped support 332. Further, the +Z side of
the support 332 is fixed to the flat surface portion 151 of the
fixing plate 150. The compliance portion 330 configured as
described above protects the head chip 300 and reduces ink pressure
fluctuations inside the reservoir R and inside the individual flow
path 353.
[0135] Referring back to FIG. 13, as described above, the ejection
head 100 distributes the ink supplied from the liquid container 5
to the plurality of nozzles N, and ejects the ink from the nozzle N
by driving the piezoelectric element 60 generated based on the
drive signal VOUT supplied via the flexible wiring substrate 346.
Here, the drive signal selection circuit 200 may be provided on the
wiring substrate 130, or may be provided on the flexible wiring
substrate 346 corresponding to each of the head chips 300.
[0136] Referring back to FIGS. 10 and 11, the ejection control
portion G4 is located on the -Z side of the flow path structure G1
and includes a wiring substrate 420. The wiring substrate 420
includes a surface 422 and a surface 421 located on the opposite
side of the surface 422 and facing the surface 422. The wiring
substrate 420 is arranged so that the surface 422 faces the side of
the flow path structure G1, the supply control portion G2, and the
liquid ejection portion G3, and the surface 421 faces the side
opposite to the flow path structure G1, the supply control portion
G2, and the liquid ejection portion G3.
[0137] A semiconductor device 423 is provided in the region on the
-X side of the surface 421 of the wiring substrate 420. The
semiconductor device 423 is a circuit component that constitutes at
least a portion of the head control circuit 21, and includes, for
example, a SoC. That is, the image information signal IP input from
the control unit 10 to the head unit 20 is input to the
semiconductor device 423. The semiconductor device 423 generates
various signals based on the input image information signal IP,
outputs corresponding control signals to various configurations
included in the head unit 20, and also outputs basic drive data dA
and dB to the drive signal output unit 50.
[0138] Further, a connector 424 is provided along the end side of
the wiring substrate 420 located on the -Y side, which is a region
on the +X side of the surface 421 of the wiring substrate 420 with
respect to the semiconductor device 423. The connector 424 is
electrically coupled to the drive signal output unit 50.
Accordingly, the basic drive data dA and dB output by the
semiconductor device 423 are supplied to the drive signal output
unit 50, and the drive signals COMA and COMB output by the drive
signal output unit 50 are propagated to the ejection portion 600
included in the ejection head 100.
[0139] Here, the wiring substrate 420 is a so-called rigid
substrate in which a copper foil portion is protected by a solder
resist or the like after a wiring pattern is formed on a base
material such as a hard composite member or a glass epoxy resin,
for example, by a copper foil or the like. The wiring substrate 420
is an example of a first rigid substrate, and the connector 424
provided on the wiring substrate 420 is an example of a first
connector. Further, the surface 422 of the wiring substrate 420 is
an example of a first surface, and the surface 421 is an example of
a second surface.
[0140] The head unit 20 configured as described above has the
ejection portion 600 including the piezoelectric element 60 and
ejecting ink, the wiring substrate 420 that propagates the drive
signals COMA and COMB to the ejection portion 600, and the
connector 424 to which the drive signals COMA and COMB are input.
Then, the head unit 20 includes the piezoelectric element 60 that
is driven with supply of the drive signals COMA and COMB from the
drive signal output unit 50, and ejects ink as a liquid by driving
the piezoelectric element 60.
[0141] Next, the configuration of the drive signal output unit 50
will be described. As shown in FIGS. 10 and 11, the drive signal
output unit 50 is located on the -Z side of the ejection control
portion G4 and includes a wiring substrate 501. The wiring
substrate 501 includes a surface 512 and a surface 511 located on
the opposite side of the surface 512 and facing the surface 512.
The wiring substrate 501 is arranged so that the surface 512 faces
the ejection control portion G4 side and the surface 511 faces the
side opposite to the ejection control portion G4. That is, the
shortest distance between the surface 421 and the surface 512 is
shorter than the shortest distance between the surface 422 and the
surface 512, and the shortest distance between the surface 512 and
the surface 421 is shorter than the shortest distance between the
surface 511 and the surface 421. In other words, the surface 421 of
the wiring substrate 420 and the surface 512 of the wiring
substrate 501 are located facing each other.
[0142] The drive circuits 51a and 51b that output the drive signals
COMA and COMB are provided on the surface 511 of the wiring
substrate 501. Specifically, the surface 511 is provided with the
integrated circuit 500, the transistors M1 and M2, the coils L1,
and the capacitor C1 included in the drive circuit 51a, which are
class D amplifier circuits of the drive circuit 51a, and the
integrated circuit 500, the transistors M1 and M2, the coils L1,
and the capacitor C1 included in the drive circuit 51b, which are
class D amplifier circuits of the drive circuit 51b.
[0143] Further, a connector 513 is provided on the surface 512 of
the wiring substrate 501. The connector 513 inputs the basic drive
data dA and dB, which are the basis of the drive signals COMA and
COMB generated by the drive circuits 51a and 51b to the drive
signal output unit 50, and outputs the drive signals COMA and COMB
output by the drive circuits 51a and 51b to the head unit 20.
[0144] As described above, the drive signal output unit 50 outputs
the drive signals COMA and COMB. Specifically, the drive signal
output unit 50 has the wiring substrate 501, the connector 513 that
outputs the drive signals, the drive circuit 51a including the DAC
510 that converts the basic drive data dA that is a digital signal
into the basic drive signal aA that is an analog signal, and the
output circuit 550 that amplifies the basic drive signal aA and
outputs the drive signal COMA, and the drive circuit 51b including
the DAC 510 that converts the basic drive data dB that is a digital
signal into the basic drive signal aB that is an analog signal, and
the output circuit 550 that amplifies the basic drive signal aB and
outputs the drive signal COMB, and outputs the drive signals COMA
and COMB to the head unit 20.
[0145] Here, the wiring substrate 501 is a so-called rigid
substrate in which a copper foil portion is protected by a solder
resist or the like after a wiring pattern is formed on a base
material such as a hard composite member or a glass epoxy resin,
for example, by a copper foil or the like. The wiring substrate 501
is an example of a second rigid substrate, and the connector 513
provided on the wiring substrate 501 is an example of a second
connector.
[0146] As described above, in the present embodiment, the drive
signal output unit 50 is located on the -Z side of the head unit 20
which is opposite to the +Z side on which the head unit 20 ejects
ink. In other words, the head unit 20 includes the nozzle plate 310
on which the nozzle N for ejecting ink is formed, and the wiring
substrate 420 and the wiring substrate 501 are provided so that the
shortest distance between the surface 422 of the wiring substrate
420 and the +Z side surface on which ink is ejected from the nozzle
N formed on the nozzle plate 310 is shorter than the shortest
distance between the surface 421 and the +Z side surface on which
ink is ejected from the nozzle N formed on the nozzle plate 310,
and the shortest distance between the surface 422 and the wiring
substrate 501 is shorter than the shortest distance between the
surface 421 and the wiring substrate 501.
[0147] That is, the wiring substrate 501 on which the drive
circuits 51a and 51b are mounted is arranged away from the nozzle
N. Accordingly, even when some of the ink ejected from the nozzle N
is turned to a mist and floats inside the liquid ejecting apparatus
1 as an ink mist, the drive circuits 51a and 51b are located away
from the nozzle N. Therefore, the possibility that the ink mist
adheres to the drive circuits 51a and 51b is reduced. As a result,
the possibility that the ink mist affects the operation of the
drive circuits 51a and 51b is reduced, and the operation of the
drive circuits 51a and 51b is stabilized. Thus, the waveform
accuracy of the drive signals COMA and COMB output by the drive
circuits 51a and 51b is improved.
[0148] Here, the surface on the +Z side where ink is ejected from
the nozzle N formed on the nozzle plate 310 is an example of an
ejection surface on which ink is ejected in the head unit 20.
[0149] Further, in the drive signal output unit 50, the electronic
components constituting the drive circuits 51a and 51b are mounted
on the surface 511 of the wiring substrate 501. In other words, the
electronic components constituting the drive circuits 51a and 51b
are not mounted on the surface 512 of the wiring substrate 501
located opposite to the surface 421 of the wiring substrate 420.
That is, no electronic components other than the connector 513 are
provided on the surface 512 of the wiring substrate 501 located
facing the surface 421 of the wiring substrate 420.
[0150] Accordingly, even when the drive circuits 51a and 51b can be
arranged further away from the nozzle N, and some of the ink
ejected from the nozzle N is turned to a mist and floats inside the
liquid ejecting apparatus 1, the possibility that the ink mist
adheres to the drive circuits 51a and 51b is further reduced.
Therefore, the possibility that the ink mist affects the operation
of the drive circuits 51a and 51b is further reduced, the operation
of the drive circuits 51a and 51b is further stabilized, and the
waveform accuracy of the drive signals COMA and COMB output by the
drive circuits 51a and 51b is further improved.
[0151] Further, since the drive circuits 51a and 51b supply the
drive signals COMA and COMB to the plurality of nozzles N included
in the head unit 20, heat generation becomes large. By not
providing the drive circuits 51a and 51b, which may generate a
large amount of heat, on the surface 512 of the wiring substrate
501 located facing the surface 421 of the wiring substrate 420, the
possibility of heat generated in the drive circuits 51a and 51b
staying between the surface 421 of the wiring substrate 420 and the
surface 512 of the wiring substrate 501 is reduced, and the heat
dissipation efficiency of the drive circuits 51a and 51b can be
improved. In addition, the drive circuits 51a and 51b, which may
generate a large amount of heat, can be arranged away from the
ejection head 100 in which ink is stored, and as a result, the
possibility that the heat generated in the drive circuits 51a and
51b is propagated to the ink is reduced. Therefore, the possibility
that the physical properties of the ink will change due to heat is
reduced, and as a result, the ejection accuracy of the ink ejected
from the head unit 20 is improved.
[0152] Next, the arrangement of the wiring substrate 420 included
in the head unit 20 and the wiring substrate 501 included in the
drive signal output unit 50, and the details of the electrical
coupling will be described. FIG. 15 is a plan view of the head unit
20 and the drive signal output unit 50 shown in FIGS. 10 and 11
when viewed from the +Z side. FIG. 16 is a side view of the wiring
substrate 420 included in the head unit 20 and the wiring substrate
501 included in the drive signal output unit 50 shown in FIGS. 10
and 11 when viewed from the -X side.
[0153] As shown in FIGS. 15 and 16, in the liquid ejecting
apparatus 1 according to the present embodiment, the wiring
substrate 420 included in the head unit 20 and the wiring substrate
501 included in the drive signal output unit 50 are electrically
coupled by fitting the connector 424 located on the surface 421 of
the wiring substrate 420 and the connector 513 located on the
surface 512 of the wiring substrate 501 in a state where the
surface 421 of the wiring substrate 420 and the surface 512 of the
wiring substrate 501 face each other. In other words, the wiring
substrate 420 and the wiring substrate 501 are stacked and coupled
by fitting the connector 424 and the connector 513 so that the
terminal included in the connector 424 and the terminal included in
the connector 513 are in direct contact with each other. Therefore,
the connector 424 and the connector 513 in the present embodiment
are board to board (BtoB) connectors, respectively, and when the
wiring substrate 420 the wiring substrate 501 are stacked and
coupled by the BtoB connectors, the basic drive data dA and dB and
the drive signals COMA and COMB are propagated between the wiring
substrate 420 and the wiring substrate 501.
[0154] Here, as shown in FIG. 15, when the head unit 20 and the
drive signal output unit 50 are viewed in a plan view from the +Z
side to the -Z side along the Z direction in which ink is ejected
from the ejection portion 600, the wiring substrate 501 included in
the drive signal output unit 50 is located so as to overlap the
wiring substrate 420 included in the head unit 20. Accordingly,
even when some of the ink ejected from the nozzle N is turned to a
mist, and the ink mist floats inside the liquid ejecting apparatus
1, the wiring substrate 420 included in the head unit 20 functions
as a protection member for reducing the possibility that the ink
mist adheres to the drive circuits 51a and 51b. Therefore, the
possibility that the ink mist adheres to the drive circuits 51a and
51b is further reduced, as a result, the possibility that the ink
mist affects the operation of the drive circuits 51a and 51b is
further reduced, the operation of the drive circuits 51a and 51b is
further stabilized, and the waveform accuracy of the drive signals
COMA and COMB output by the drive circuits 51a and 51b is further
improved.
[0155] Therefore, when the head unit 20 and the drive signal output
unit 50 are viewed in a plan view from the +Z side to the -Z side
along the Z direction in which ink is ejected from the ejection
portion 600, at least a portion of the wiring substrate 501
included in the drive signal output unit 50 may be located so as to
overlap the wiring substrate 420 included in the head unit 20, and
as shown in FIG. 15, when the head unit 20 and the drive signal
output unit 50 are viewed in a plan view from the +Z side to the -Z
side along the Z direction in which ink is ejected from the
ejection portion 600, it is more preferable that the entire wiring
substrate 501 of the drive signal output unit 50 is located so as
to overlap the wiring substrate 420 of the head unit 20.
Accordingly, the possibility that the ink mist affects the
operation of the drive circuits 51a and 51b can be further reduced,
the operation of the drive circuits 51a and 51b can be further
stabilized, and the waveform accuracy of the drive signals COMA and
COMB output by the drive circuits 51a and 51b can be further
improved.
[0156] Here, a specific example of the connectors 513 and 424 that
electrically couple the wiring substrate 420 of the head unit 20
and the wiring substrate 501 of the drive signal output unit 50
will be described.
[0157] FIGS. 17A to 17C are diagrams showing the structure of the
connector 513. Further, FIG. 18 is a cross-sectional view taken
along line XVIII-XVIII shown in FIGS. 17A to 17C. As shown in FIGS.
17A to 18, the connector 513 in the present embodiment has a
straight type receptacle shape, and includes insulators 710 and
720, fixing portions 730, a plurality of substrate connection
terminals 742, a plurality of substrate connection terminals 752, a
plurality of contact terminals 744, and a plurality of contact
terminals 754. Here, in FIGS. 17A to 17C, as FIG. 17A, when the
plurality of substrate connection terminals 742 and the plurality
of substrate connection terminals 752 of the connector 513 are
coupled to the wiring substrate 501, the case where the connector
513 is viewed from the normal direction of the wiring substrate 501
is shown, as FIG. 17B, the case where the connector 513 is
orthogonal to the normal direction of the wiring substrate 501 and
the connector 513 is viewed from the longitudinal direction is
shown, and as FIG. 17C, the case where the connector 513 is
orthogonal to the normal direction of the wiring substrate 501 and
the connector 513 is viewed from the lateral direction is
shown.
[0158] The insulators 710 and 720 function as an insulating member
that insulates between the plurality of substrate connection
terminals 742, between the plurality of substrate connection
terminals 752, between the plurality of contact terminals 744, and
between the plurality of contact terminals 754. Further, the
insulator 720 is formed with a protrusion 722 and a plug mounting
portion 724. The plug mounting portion 724 has an opening on the
surface of the connector 513 facing the plurality of substrate
connection terminals 742 and the plurality of substrate connection
terminals 752 and is a substantially rectangular
parallelepiped-shaped insertion hole formed along the longitudinal
direction of the connector 513, and the connector 424 to be
described later is inserted into the plug mounting portion 724. The
protrusion 722 is a substantially rectangular parallelepiped-shaped
protrusion formed inside the plug mounting portion 724 along the
longitudinal direction of the connector 513, and functions as a
guide for guiding the connector 424 inserted into the plug mounting
portion 724 into a predetermined position. At least one of such
insulators 710 and 720 are made of a liquid crystal polymer (LCP)
containing glass fiber. In other words, the insulators 710 and 720
contain glass fiber.
[0159] The liquid ejecting apparatus 1 ejects a liquid on a fiber
material including a cloth such as paper or clothing and a wide
variety of media such as metal and plastic to form a desired image
on the medium. Therefore, the types of inks vary depending on the
type of medium used, such as water-based inks such as dye-based
inks and pigment-based inks, UV-curable inks that are cured by
irradiation with ultraviolet rays, and oil-based inks. In
particular, in recent years, the development of semiconductor
manufacturing technology using ink jet technology has progressed,
the technical field in which the liquid ejecting apparatus 1 is
used has become wider, and as a result, the types of liquids that
can be used in the liquid ejecting apparatus 1 have increased.
[0160] In the liquid ejecting apparatus 1 in which such a wide
variety of liquids can be used, the connector 513 is required to
have high corrosion resistance because the physical properties
differ depending on the type of ink used. In particular, the
insulators 710 and 720 that ensure the insulation performance
between the terminals that propagate the signal are required to
have high corrosion resistance from the viewpoint of reducing the
possibility that the signal accuracy is lowered due to the
deterioration of the insulation performance. In the insulators 710
and 720 which are required to have such high corrosion resistance,
by including glass fiber in the material, compared with the case
where the insulators 710 and 720 are made of only polyethylene
terephthalate (PET) resin or polypropylene (PP) resin, high
corrosion resistance can be realized, and as a result, the
possibility of the deterioration of the insulation performance of
the connector 513 is reduced, and the possibility of the
deterioration of the accuracy of the signal propagated through the
connector 513 is also reduced. That is, since the insulators 710
and 720 contain glass fiber, it is possible to reduce the
possibility that the reliability of the connector 513 is lowered
even in the liquid ejecting apparatus 1 in which a wide variety of
inks are used.
[0161] Here, at least one of the insulators 710 and 720 included in
the connector 513 is an example of a second insulator portion.
[0162] The plurality of substrate connection terminals 742 are
arranged side by side along one side of the connector 513 located
in the longitudinal direction. The plurality of substrate
connection terminals 742 are electrically coupled to the wiring
substrate 501 by solder or the like. Further, the plurality of
substrate connection terminals 752 are arranged side by side along
the other side of the connector 513 located in the longitudinal
direction. The plurality of substrate connection terminals 752 are
electrically coupled to the wiring substrate 501 by solder or the
like. The plurality of contact terminals 744 are arranged side by
side along the longitudinal direction of the connector 513 on the
surface of the substantially rectangular parallelepiped-shaped
protrusion 722 formed along the longitudinal direction of the
connector 513 on the side of the plurality of substrate connection
terminals 742. Further, the plurality of contact terminals 754 are
arranged side by side along the longitudinal direction of the
connector 513 on the surface of the substantially rectangular
parallelepiped-shaped protrusion 722 formed along the longitudinal
direction of the connector 513 on the side of the plurality of
substrate connection terminals 752.
[0163] As shown in FIG. 18, the plurality of substrate connection
terminals 742 and the plurality of contact terminals 744 are
electrically coupled to each other inside the insulators 710 and
720 on a one-to-one basis, and the plurality of substrate
connection terminals 752 and the plurality of contact terminals 754
are electrically coupled to each other inside the insulators 710
and 720 on a one-to-one basis. Here, in the following description,
the one-to-one corresponding substrate connection terminal 742 and
contact terminal 744 may be collectively referred to as a
connection terminal 740, and the one-to-one corresponding substrate
connection terminal 752 and contact terminal 754 may be
collectively referred to as a connection terminal 750. That is, the
connector 513 includes a plurality of connection terminals 740
arranged side by side along one side located in the longitudinal
direction, and a plurality of connection terminals 750 arranged
side by side along the other side located in the longitudinal
direction.
[0164] The plurality of connection terminals 740 and the plurality
of connection terminals 750 included in such a connector 513 are
each formed by plating a copper alloy with gold. As described
above, since the connector 513 is used in the liquid ejecting
apparatus 1 in which a wide variety of inks can be used, high
corrosion resistance is required. If the plurality of connection
terminals 740 and the plurality of connection terminals 750 are
corroded, the impedances of the plurality of connection terminals
740 and the plurality of connection terminals 750 change, and as a
result, the accuracy of the signal propagated through the plurality
of connection terminals 740 and the plurality of connection
terminals 750 is lowered. The ink ejection characteristics of the
liquid ejecting apparatus 1 may deteriorate due to the
deterioration of the accuracy of the signal propagated through the
plurality of connection terminals 740 and the plurality of
connection terminals 750. In response to such a problem, since each
of the plurality of connection terminals 740 and the plurality of
connection terminals 750 contains a copper alloy, it is possible to
reduce the possibility that the plurality of connection terminals
740 and the plurality of connection terminals 750 are corroded by
ink, and it is possible to reduce the possibility that the accuracy
of the signal propagated through the connector 513 is lowered.
[0165] Further, it is preferable that the plurality of connection
terminals 740 and the plurality of connection terminals 750
containing a copper alloy are plated with a metal having a small
resistance value. The plurality of connection terminals 740 and the
plurality of connection terminals 750 propagate the basic drive
data dA and dB supplied to the drive signal output unit 50 and the
drive signals COMA and COMB output by the drive signal output unit
50. By plating the plurality of connection terminals 740 and the
plurality of connection terminals 750 with a metal having a small
resistance value, the impedance of the signal propagation path can
be reduced, and as a result, the signal accuracy of the basic drive
data dA and dB and the drive signals COMA and COMB can be further
improved.
[0166] Here, as the metal used for the plating treatment applied to
the plurality of connection terminals 740 and the plurality of
connection terminals 750 containing the copper alloy, it is
preferable to use gold, silver, aluminum, or the like, and it is
particularly preferable to perform the plating treatment using gold
having a small resistivity. Accordingly, both high corrosion
resistance and high conductivity can be realized.
[0167] Here, among the plurality of connection terminals 740 and
the plurality of connection terminals 750, the terminal that
propagates the drive signals COMA and COMB is an example of a
second terminal.
[0168] The fixing portions 730 are located along each of the two
short sides of the connector 513 facing each other in the
longitudinal direction. The fixing portion 730 fixes the connector
513 to the wiring substrate 501 by fitting with the wiring
substrate 501. In other words, the fixing portion 730 is fixed to
the wiring substrate 501. Accordingly, even when an unintended
stress is applied to the connector 513, the stress is absorbed by
the fixing portion 730. Therefore, the possibility that an
unintended stress due to the stress is applied to the connection
terminals 740 and 750 to which the basic drive data dA and dB and
the drive signals COMA and COMB are propagated is reduced, and as a
result, the possibility of problems such as pattern peeling
occurring on the wiring substrate 501 to which the connection
terminals 740 and 750 are coupled is reduced.
[0169] Each of such fixing portions 730 is formed by tin-plating a
copper alloy. As described above, since the connector 513 is used
in the liquid ejecting apparatus 1 in which a wide variety of inks
can be used, high corrosion resistance is required. If the fixing
portion 730 is corroded, problems such as pattern peeling as
described above may occur, and as a result, signal accuracy may be
lowered. With respect to such a problem, since the fixing portion
730 contains the copper alloy, it is possible to reduce the
possibility that the fixing portion 730 is corroded by the ink.
[0170] Further, the fixing portion 730 has a configuration for
fixing the connector 513 to the wiring substrate 501, and therefore
is not a configuration used for propagating a signal other than a
signal having a constant potential such as a ground potential.
Therefore, it is preferable that the fixing portion 730 is plated
with tin, which is hard to be deformed and is inexpensive.
Accordingly, the strength of fixing to the wiring substrate 501 can
be increased by the fixing portion 730. Further, the fixing portion
730 may be fixed to the wiring substrate 501 by soldering. In this
case, since the fixing portion 730 is plated with tin, the joint
strength between the fixing portion 730 and the wiring substrate
501 can be increased.
[0171] Here, the fixing portion 730 fixed to the wiring substrate
501 is an example of a second fixing portion.
[0172] FIGS. 19A to 19C are diagrams showing the structure of the
connector 424. Further, FIG. 20 is a cross-sectional view taken
along line XX-XX shown in FIGS. 19A to 19C. As shown in FIGS. 19A
to 20, the connector 424 in the present embodiment has a straight
type plug shape, and includes an insulator 810, fixing portions
830, a plurality of substrate connection terminals 842, a plurality
of substrate connection terminals 852, a plurality of contact
terminals 844, and a plurality of contact terminals 854. Here, in
FIGS. 19A to 19C, as FIG. 19A, when the plurality of substrate
connection terminals 842 and the plurality of substrate connection
terminals 852 of the connector 424 are coupled to the wiring
substrate 420, the case where the connector 424 is viewed from the
normal direction of the wiring substrate 420 is shown, as FIG. 19B,
the case where the connector 424 is orthogonal to the normal
direction of the wiring substrate 420 and the connector 424 is
viewed from the longitudinal direction is shown, and as FIG. 19C,
the case where the connector 424 is orthogonal to the normal
direction of the wiring substrate 420 and the connector 424 is
viewed from the lateral direction is shown.
[0173] The insulator 810 functions as an insulating member that
insulates between the plurality of substrate connection terminals
842, between the plurality of substrate connection terminals 852,
between the plurality of contact terminals 844, and between the
plurality of contact terminals 854. Further, the insulator 810 is
formed with a receptacle mounting portion 824. The receptacle
mounting portion 824 has an opening on the surface of the connector
424 facing the plurality of substrate connection terminals 842 and
the plurality of substrate connection terminals 852 and is a
substantially rectangular parallelepiped-shaped insertion hole
formed along the longitudinal direction of the connector 424, and
the protrusion 722 of the connector 513 described above is inserted
into the receptacle mounting portion 824. Such an insulator 810 is
made of a liquid crystal polymer (LCP) containing glass fiber. In
other words, the insulator 810 contains glass fiber.
[0174] Similar to the connector 513, in the liquid ejecting
apparatus 1 in which a wide variety of liquids can be used, the
insulator 810 that ensures the insulation performance between the
terminals that propagate the signal are required to have high
corrosion resistance from the viewpoint of reducing the possibility
that the signal accuracy is lowered due to the deterioration of the
insulation performance. In the insulator 810 which is required to
have such high corrosion resistance, by including glass fiber in
the material, compared with the case where the insulator 810 is
made of only PET resin or PP resin, high corrosion resistance can
be realized, and as a result, the possibility of the deterioration
of the insulation performance of the connector 424 is reduced, and
the possibility of the deterioration of the accuracy of the signal
propagated through the connector 424 is also reduced. That is,
since the insulator 810 contains glass fiber, it is possible to
reduce the possibility that the reliability of the connector 424 is
lowered even in the liquid ejecting apparatus 1 in which a wide
variety of inks are used.
[0175] Here, the insulator 810 included in the connector 424 is an
example of a first insulator portion.
[0176] The plurality of substrate connection terminals 842 are
arranged side by side along one side of the connector 424 located
in the longitudinal direction. The plurality of substrate
connection terminals 842 are electrically coupled to the wiring
substrate 420 by solder or the like. Further, the plurality of
substrate connection terminals 852 are arranged side by side along
the other side of the connector 424 located in the longitudinal
direction. The plurality of substrate connection terminals 852 are
electrically coupled to the wiring substrate 420 by solder or the
like. The plurality of contact terminals 844 are arranged side by
side along the longitudinal direction of the connector 424 on the
surface of the substantially rectangular parallelepiped-shaped
receptacle mounting portion 824 formed along the longitudinal
direction of the connector 424 on the side of the plurality of
substrate connection terminals 842. Further, the plurality of
contact terminals 854 are arranged side by side along the
longitudinal direction of the connector 424 on the surface of the
substantially rectangular parallelepiped-shaped receptacle mounting
portion 824 formed along the longitudinal direction of the
connector 424 on the side of the plurality of substrate connection
terminals 852.
[0177] As shown in FIG. 20, the plurality of substrate connection
terminals 842 and the plurality of contact terminals 844 are
electrically coupled to each other inside the insulator 810 on a
one-to-one basis, and the plurality of substrate connection
terminals 852 and the plurality of contact terminals 854 are
electrically coupled to each other inside the insulator 810 on a
one-to-one basis. Here, in the following description, the
one-to-one corresponding substrate connection terminal 842 and
contact terminal 844 may be collectively referred to as a
connection terminal 840, and the one-to-one corresponding substrate
connection terminal 852 and contact terminal 854 may be
collectively referred to as a connection terminal 850. That is, the
connector 424 includes a plurality of connection terminals 840
arranged side by side along one side located in the longitudinal
direction, and a plurality of connection terminals 850 arranged
side by side along the other side located in the longitudinal
direction.
[0178] The plurality of connection terminals 840 and the plurality
of connection terminals 850 included in such a connector 424 are
each formed by plating a copper alloy with gold. As described
above, since the connector 424 is used in the liquid ejecting
apparatus 1 in which a wide variety of inks can be used, high
corrosion resistance is required. If the plurality of connection
terminals 840 and the plurality of connection terminals 850 are
corroded, the impedances of the plurality of connection terminals
840 and the plurality of connection terminals 850 change, and as a
result, the accuracy of the signal propagated through the plurality
of connection terminals 840 and the plurality of connection
terminals 850 is lowered. The ink ejection characteristics of the
liquid ejecting apparatus 1 may deteriorate due to the
deterioration of the accuracy of the signal propagated through the
plurality of connection terminals 840 and the plurality of
connection terminals 850. In response to such a problem, since each
of the plurality of connection terminals 840 and the plurality of
connection terminals 850 contains a copper alloy, it is possible to
reduce the possibility that the plurality of connection terminals
840 and the plurality of connection terminals 850 are corroded by
ink, and it is possible to reduce the possibility that the accuracy
of the signal propagated through the connector 424 is lowered.
[0179] Further, it is preferable that the plurality of connection
terminals 840 and the plurality of connection terminals 850
containing a copper alloy are plated with a metal having a small
resistance value. The plurality of connection terminals 840 and the
plurality of connection terminals 850 propagate the basic drive
data dA and dB supplied to the drive signal output unit 50 and the
drive signals COMA and COMB output by the drive signal output unit
50. By plating the plurality of connection terminals 840 and the
plurality of connection terminals 850 with a metal having a small
resistance value, the impedance of the signal propagation path can
be reduced, and as a result, the signal accuracy of the basic drive
data dA and dB and the drive signals COMA and COMB can be further
improved.
[0180] Here, as the metal used for the plating treatment applied to
the plurality of connection terminals 840 and the plurality of
connection terminals 850 containing the copper alloy, it is
preferable to use gold, silver, aluminum, or the like, and it is
particularly preferable to perform the plating treatment using gold
having a small resistivity. Accordingly, both high corrosion
resistance and high conductivity can be realized.
[0181] Here, among the plurality of connection terminals 840 and
the plurality of connection terminals 850, the terminal that
propagates the drive signals COMA and COMB is an example of a first
terminal.
[0182] The fixing portions 830 are located along each of the two
short sides of the connector 424 facing each other in the
longitudinal direction. The fixing portion 830 fixes the connector
424 to the wiring substrate 420 by fitting with the wiring
substrate 420. In other words, the fixing portion 830 is fixed to
the wiring substrate 420. Accordingly, even when an unintended
stress is applied to the connector 424, the stress is absorbed by
the fixing portion 830. Therefore, the possibility that an
unintended stress due to the stress is applied to the connection
terminals 840 and 850 to which the basic drive data dA and dB and
the drive signals COMA and COMB are propagated is reduced, and as a
result, the possibility of problems such as pattern peeling
occurring on the wiring substrate 420 to which the connection
terminals 840 and 850 are coupled is reduced.
[0183] Each of such fixing portions 830 is formed by tin-plating a
copper alloy. As described above, since the connector 424 is used
in the liquid ejecting apparatus 1 in which a wide variety of inks
can be used, high corrosion resistance is required. If the fixing
portion 830 is corroded, problems such as pattern peeling as
described above may occur, and as a result, signal accuracy may be
lowered. With respect to such a problem, since the fixing portion
830 contains the copper alloy, it is possible to reduce the
possibility that the fixing portion 830 is corroded by the ink.
[0184] Further, the fixing portion 830 has a configuration for
fixing the connector 424 to the wiring substrate 420, and therefore
is not a configuration used for propagating a signal other than a
signal having a constant potential such as a ground potential.
Therefore, it is preferable that the fixing portion 830 is plated
with tin, which is hard to be deformed and is inexpensive.
Accordingly, the strength of fixing to the wiring substrate 501 can
be increased by the fixing portion 830. Further, the fixing portion
830 may be fixed to the wiring substrate 420 by soldering. In this
case, since the fixing portion 830 is plated with tin, the joint
strength between the fixing portion 830 and the wiring substrate
420 can be increased.
[0185] Here, the fixing portion 830 fixed to the wiring substrate
420 is an example of a first fixing portion.
[0186] The connector 513 and the connector 424 configured as
described above are fitted so that the connection terminal 740 and
the connection terminal 840 are in direct contact with each other
and the connection terminal 750 and the connection terminal 850 are
in direct contact with each other, thereby electrically coupling
the wiring substrate 501 and the wiring substrate 420.
[0187] FIG. 21 is a diagram showing a state where the connector 513
and the connector 424 are fitted. As shown in FIG. 21, one end of
the connection terminals 740 and 750 of the connector 513 is
electrically coupled to the wiring substrate 501. Further, the
insulator 810 of the connector 424 is inserted into the plug
mounting portion 724 of the connector 513. Further, the protrusion
722 of the connector 513 is inserted into the receptacle mounting
portion 824 of the connector 424. Accordingly, the connector 513
and the connector 424 are fitted.
[0188] In this case, the connection terminal 740 provided on the
protrusion 722 of the connector 513 comes into contact with the
connection terminal 840 provided on the receptacle mounting portion
824 of the connector 424, and the connection terminal 750 provided
on the protrusion 722 of the connector 513 comes into contact with
the connection terminal 850 provided on the receptacle mounting
portion 824 of the connector 424. Accordingly, the wiring substrate
501 to which the connector 513 is fixed and the wiring substrate
420 to which the connector 424 is fixed are electrically coupled to
each other, and the basic drive data dA and dB are supplied to the
drive signal output unit 50 including the wiring substrate 501, and
the drive signals COMA and COMB output by the drive signal output
unit 50 are supplied to the head unit 20 including the wiring
substrate 420.
[0189] The drive signals COMA and COMB shared by the head unit 20
are propagated through the wiring substrate 420 and then supplied
to each of the ejection heads 100-1 to 100-6, and the drive signal
selection circuit 200 selects or does not select the signal
waveforms included in the drive signals COMA and COMB. As a result,
the drive signal VOUT is generated and supplied to the
piezoelectric element 60 of the ejection portion 600 included in
the head chip 300.
[0190] Here, as shown in FIG. 21, an interference space SP is
formed between the connection terminal 740 and the insulator 720 of
the connector 513 and between the connection terminal 750 and the
insulator 720. The interference space SP forms a movable area in
which the connection terminals 740 and 750 and the insulator 720
can move with respect to the insulator 710. Since the connector 513
has the movable area, even if there is a misalignment between the
connector 513 and the connector 424 when the connector 513 and the
connector 424 are fitted, the connector 513 and the connector 424
can be fitted so that the connection terminal 740 and the
connection terminal 840 are in direct contact with each other and
the connection terminal 750 and the connection terminal 850 are in
direct contact with each other. That is, the connector 513 is
configured as a floating connector that absorbs an error that
occurs when the connector 513 and the connector 424 are fitted.
[0191] Although the connector 513 has been described as a floating
connector in the present embodiment, the connector 424 may be a
floating connector, and both the connector 513 and the connector
424 may be floating connectors.
[0192] In the present embodiment, although it has been described
that the connector 513 has a straight type receptacle shape, and
the connector 424 has a straight type plug shape, the connector 424
may have a straight type receptacle shape, and the connector 513
may have a straight type plug shape. That is, one of the connector
424 and the connector 513 has a receptacle shape, and the other of
the connector 424 and the connector 513 has a plug shape.
[0193] However, as shown in the present embodiment, it is
preferable that the connector 513 has a straight type receptacle
shape and the connector 424 has a straight type plug shape.
[0194] As described above, inside the liquid ejecting apparatus 1,
some of the ejected ink is turned to a mist, and the ink mist
floats. If the connector 424 has a straight type receptacle shape,
the ink mist floating inside the liquid ejecting apparatus 1 stays
inside the plug mounting portion 724 because the plug mounting
portion 724 is a recess, and as a result, there is a possibility
that a short-circuit abnormality may occur between each of the
plurality of connection terminals 740 and 750. By making the shape
of the connector 513 a straight type receptacle shape and the shape
of the connector 424 a straight type plug shape, the possibility of
ink mist staying inside the plug mounting portion 724 is reduced,
and as a result, the possibility that a short-circuit abnormality
occurs between each of the plurality of connection terminals 740
and 750 due to the ink mist is reduced.
6. Effect
[0195] As described above, in the liquid ejecting apparatus 1
according to the present embodiment, the head unit 20 that ejects
ink based on the drive signals COMA and COMB and the drive signal
output unit 50 that outputs the drive signals COMA and COMB to the
head unit 20 are electrically coupled by a so-called BtoB connector
in which the connector 424 and the connector 513 are fitted so that
the terminal included in the connector 424 and the terminal
included in the connector 513 are in direct contact with each
other. Accordingly, the drive signal output unit 50 can be arranged
in the vicinity of the head unit 20, and the area occupied by the
head unit 20 and the drive signal output unit 50 inside the liquid
ejecting apparatus 1 can be reduced compared with the configuration
in which the head unit 20 and the drive signal output unit 50 are
electrically coupled using a cable such as an FFC and the drive
signals COMA and COMB are supplied to the head unit 20. As a
result, the size of the liquid ejecting apparatus 1 can be
reduced.
[0196] Then, since both the wiring substrate 420 and the wiring
substrate 501 are composed of a rigid substrate, when the wiring
substrate 420 and the wiring substrate 501 are coupled by using the
connector 424 and the connector 513, the possibility of deformation
of the wiring substrates 420 and 501 is reduced. As a result, the
possibility that the wiring impedance of the wiring substrates 420
and 501 fluctuates before and after coupling the wiring substrate
420 and the wiring substrate 501 by using the connector 424 and the
connector 513 is reduced. That is, the possibility that the wiring
impedance of the propagation path through which the drive signals
COMA and COMB propagate fluctuates is reduced, and the possibility
that waveform distortion due to the fluctuation of the wiring
impedance occurs in the drive signals COMA and COMB is also
reduced.
[0197] Further, when the wiring substrate 420 and the wiring
substrate 501 are coupled by a cable such as an FFC, the wiring
impedance of the propagation path through which the drive signals
COMA and COMB propagate fluctuates depending on the deformation of
the cable. However, in the liquid ejecting apparatus 1 according to
the present embodiment, the head unit 20 and the drive signal
output unit 50 are electrically coupled by a so-called BtoB
connector in which the connector 424 and the connector 513 are
fitted so that the terminal included in the connector 424 and the
terminal included in the connector 513 are in direct contact with
each other without using a cable such as an FFC. Therefore, there
is no possibility that the wiring impedance fluctuates due to such
a cable, and the possibility that waveform distortion due to the
fluctuation of the wiring impedance occurs in the drive signals
COMA and COMB is reduced.
[0198] As described above, in the liquid ejecting apparatus 1
according to the present embodiment, in addition to making it
possible to reduce the size of the liquid ejecting apparatus 1, it
is possible to reduce the possibility that waveform distortion
occurs in the drive signals COMA and COMB propagating between the
drive signal output unit 50 and the head unit 20.
[0199] Further, in the liquid ejecting apparatus 1 according to the
present embodiment, the connector 424 is configured as a floating
connector that absorbs an error that occurs when the connector 513
is fitted to the connector 424. Accordingly, the reliability of
contact between the terminal included in the connector 424 and the
terminal included in the connector 513 when the connector 513 is
fitted to the connector 424 can be further improved, and it is
possible to further reduce the possibility that waveform distortion
occurs in the drive signals COMA and COMB propagating between the
drive signal output unit 50 and the head unit 20.
[0200] Further, since the connector 424 is configured as a floating
connector, in the liquid ejecting apparatus 1, for example, the
possibility of loosening the fitting between the connector 424 and
the connector 513 due to vibration or the like caused by the drive
of the motor generated during the transportation of the medium is
reduced. As a result, the reliability of the electrical coupling
between the wiring substrate 420 and the wiring substrate 501 by
the connector 424 and the connector 513 can be further
improved.
[0201] Further, in the liquid ejecting apparatus 1 according to the
present embodiment, the wiring substrate 420 and the wiring
substrate 501 are stacked and coupled by fitting the connector 424
and the connector 513 so that the terminal included in the
connector 424 and the terminal included in the connector 513 are in
direct contact with each other. Accordingly, the wiring substrate
501 can be provided in the vicinity along the wiring substrate 420,
and the area occupied by the head unit 20 and the drive signal
output unit 50 inside the liquid ejecting apparatus 1 can be
further reduced. That is, the size of the liquid ejecting apparatus
1 can be further reduced in a state where the maintainability of
the liquid ejecting apparatus 1 is improved.
[0202] Further, in the liquid ejecting apparatus 1 according to the
present embodiment, the insulators 710 and 720 included in the
connector 424 and the insulator 810 included in the connector 513
contain glass fiber, the plurality of connection terminals 740 and
750 included in the connector 424 and the plurality of connection
terminals 840 and 850 included in the connector 513 contain a
gold-plated copper alloy, and the fixing portion 730 included in
the connector 424 and the fixing portion 830 included in the
connector 513 contain a tin-plated copper alloy. Even in the liquid
ejecting apparatus 1 which is used in a wide range of fields and
has a wide variety of liquids to be ejected, the possibility that
the connectors 424 and 513 are corroded by the physical properties
of the ejected liquid, and as a result, an abnormality occurs in
the operation of the liquid ejecting apparatus 1 is reduced.
[0203] The embodiments and modification examples have been
described above, but the present disclosure is not limited to these
embodiments and can be carried out in various modes without
departing from the scope of the disclosure. For example, it is
possible to combine the above-described embodiments as
appropriate.
[0204] The present disclosure includes configurations that are
substantially the same as the configurations described in the
embodiments (for example, configurations having the same function,
method, and result, or configurations having the same object and
effect). Further, the present disclosure includes configurations in
which non-essential parts of the configurations described in the
embodiments are replaced. In addition, the present disclosure
includes configurations that achieve the same effect as the
configurations described in the embodiments or configurations that
can achieve the same object. Further, the present disclosure
includes configurations in which known techniques are added to the
configurations described in the embodiment.
[0205] The following contents are derived from the above-described
embodiment.
[0206] According to an aspect, there is provided a liquid ejecting
apparatus including a head unit that includes a piezoelectric
element that is driven with supply of a drive signal and ejects a
liquid by driving the piezoelectric element, and a drive signal
output unit that outputs the drive signal, in which the head unit
includes an ejection portion that ejects the liquid, a first rigid
substrate that propagates the drive signal to the ejection portion,
and a first connector including a first terminal to which the drive
signal is input, the drive signal output unit includes a second
rigid substrate, a second connector including a second terminal
that outputs the drive signal, a D/A converter that converts basic
drive data, which is a digital signal, into a basic drive signal,
which is an analog signal, and a drive signal output circuit that
amplifies the basic drive signal and outputs the drive signal, the
first connector is provided on the first rigid substrate, the
second connector, the D/A converter, and the drive signal output
circuit are provided on the second rigid substrate, one of the
first connector and the second connector has a receptacle shape,
the other of the first connector and the second connector has a
plug shape, and the first connector and the second connector are
fitted so that the first terminal and the second terminal are in
direct contact with each other.
[0207] According to this liquid ejecting apparatus, since the head
unit includes a first rigid substrate which is a hard substrate
which is hard to be deformed, and the drive signal output unit
includes a second rigid substrate which is a hard substrate which
is hard to be deformed, the possibility of deformation of the first
rigid substrate and the second rigid substrate due to the operation
of the liquid ejecting apparatus is reduced. As a result, the
possibility that the impedance of the wiring through which the
drive signal is propagated changes due to the deformation of the
first rigid substrate and the second rigid substrate is reduced.
Thus, the possibility that waveform distortion occurs in the drive
signal propagating through the head unit and the drive signal
output unit and being supplied to the ejection portion is reduced.
Further, by directly coupling the head unit and the drive signal
output unit to the first connector and the second connector, there
is no possibility of impedance conversion due to changes in the
shape of a cable that occur when the head unit and drive signal
output unit are coupled via the cable, and thus, the possibility
that waveform distortion occurs in the drive signal propagating
through the head unit and the drive signal output unit and being
supplied to the ejection portion is reduced.
[0208] In the liquid ejecting apparatus according to the aspect,
the first rigid substrate may include a first surface and a second
surface facing the first surface, the head unit may include an
ejection surface on which the liquid is ejected, and a shortest
distance between the first surface and the ejection surface may be
shorter than a shortest distance between the second surface and the
ejection surface, and a shortest distance between the second
surface and the second rigid substrate may be shorter than a
shortest distance between the first surface and the second rigid
substrate.
[0209] According to this liquid ejecting apparatus, since the first
rigid substrate is located between the second rigid substrate
included in the drive signal output unit and the ejection surface
on which the liquid is ejected from the head unit, the possibility
that a liquid mist generated by the ejected liquid adheres to the
second rigid substrate of the drive signal output unit that outputs
the drive signal is reduced. As a result, the possibility that the
waveform accuracy of the drive signal output by the drive signal
output unit is lowered due to the liquid mist adhering to the
second rigid substrate is reduced.
[0210] In the liquid ejecting apparatus according to the aspect,
when viewed in a plan view in a direction in which the liquid is
ejected from the ejection portion, the second rigid substrate may
overlap the first rigid substrate.
[0211] According to this liquid ejecting apparatus, since the
second rigid substrate included in the drive signal output unit is
located so as to overlap the first rigid substrate included in the
head unit, the first rigid substrate functions as a shielding
portion that reduces the possibility that the liquid mist generated
by the ejected liquid adheres to the second rigid substrate. As a
result, the possibility that the waveform accuracy of the drive
signal output by the drive signal output unit is lowered due to the
liquid mist adhering to the second rigid substrate is reduced.
[0212] In the liquid ejecting apparatus according to the aspect,
the first rigid substrate and the second rigid substrate may be
stacked and coupled by fitting the first connector and the second
connector so that the first terminal and the second terminal are in
direct contact with each other.
[0213] According to this liquid ejecting apparatus, the drive
signal output unit can be arranged in the vicinity of the head
unit, and the size of the liquid ejecting apparatus can be
reduced.
[0214] In the liquid ejecting apparatus according to the aspect,
the first connector may have a plug shape, and the second connector
may have a receptacle shape.
[0215] According to this liquid ejecting apparatus, the possibility
of liquid accumulating in the first connector having a plug shape
located downward in the ejection direction is reduced. As a result,
the possibility of a short-circuit abnormality occurring due to the
accumulated liquid between the terminals included in the first
connector is reduced.
[0216] In the liquid ejecting apparatus according to the aspect, at
least one of the first connector and the second connector may be a
floating connector.
[0217] In the liquid ejecting apparatus according to the aspect,
the first connector may include a first insulator portion, the
second connector may include a second insulator portion, and at
least one of the first insulator portion and the second insulator
portion may contain glass fiber.
[0218] According to this liquid ejecting apparatus, since the error
that occurs when the first connector and the second connector are
fitted can be absorbed, the first connector and the second
connector can be more easily coupled.
[0219] In the liquid ejecting apparatus according to the aspect, at
least one of the first terminal and the second terminal may contain
a copper alloy.
[0220] According to this liquid ejecting apparatus, even in a
liquid ejecting apparatus in which a wide variety of liquids are
used, the corrosion resistance of the first terminal and the second
terminal is improved by configuring at least one of the first
terminal and the second terminal to contain a copper alloy, and the
reliability of the drive signal propagated through the first
terminal and the second terminal is improved.
[0221] In the liquid ejecting apparatus according to the aspect, at
least one of the first terminal and the second terminal may be
gold-plated.
[0222] According to this liquid ejecting apparatus, by plating at
least one of the first terminal and the second terminal with gold
having a small resistivity, the signal distortion caused by the
impedance of the first terminal and the second terminal is reduced,
and the reliability of the drive signal propagated through the
first terminal and the second terminal is improved.
[0223] In the liquid ejecting apparatus according to the aspect,
the first connector may include a first fixing portion fixed to the
first rigid substrate, the second connector may include a second
fixing portion fixed to the second rigid substrate, and at least
one of the first fixing portion and the second fixing portion may
contain a copper alloy.
[0224] According to this liquid ejecting apparatus, even in a
liquid ejecting apparatus in which a wide variety of liquids are
used, the corrosion resistance of the first fixing portion and the
second fixing portion is further improved by configuring at least
one of the first fixing portion and the second fixing portion to
contain a copper alloy, and the reliability of the drive signal
propagated through the first connector and the second connector
fixed by the first fixing portion and the second fixing portion is
improved.
[0225] In the liquid ejecting apparatus according to the aspect, at
least one of the first fixing portion and the second fixing portion
may be tin-plated.
[0226] According to this liquid ejecting apparatus, the corrosion
resistance of the first fixing portion and the second fixing
portion is further improved by tin-plating at least one of the
first fixing portion and the second fixing portion, and the
reliability of the drive signal propagated through the first
connector and the second connector fixed by the first fixing
portion and the second fixing portion is improved.
* * * * *